Investigation of the Instantaneous Velocity Distribution in the Volute of a Centrifugal Pump Citation Binder, Raymond Charles (1936) Investigation of the Instantaneous Velocity Distribution in the Volute of a Centrifugal Pump. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/vc5c-xj91. https://resolver.caltech.edu/CaltechTHESIS:11052024-211420363 Abstract No abstract. Item Type: Thesis (Dissertation (Ph.D.)) Subject Keywords: (Mechanical Engineering) Degree Grantor: California Institute of Technology Division: Engineering and Applied Science Major Option: Mechanical Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Knapp, Robert T. Thesis Committee: Unknown, Unknown Defense Date: 1 January 1936 Record Number: CaltechTHESIS:11052024-211420363 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:11052024-211420363 DOI: 10.7907/vc5c-xj91 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16833 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 13 Nov 2024 17:36 Last Modified: 13 Nov 2024 17:56 Thesis Files PDF - Final Version See Usage Policy. 42MB PDF (Figure 40 - page 66) - Supplemental Material See Usage Policy. 6MB PDF (Figure 41 - page 67) - Supplemental Material See Usage Policy. 7MB PDF (Figure 43 - page 69) - Supplemental Material See Usage Policy. 9MB PDF (Figure 44 - page 70) - Supplemental Material See Usage Policy. 6MB PDF (Figure 46 - page 72) - Supplemental Material See Usage Policy. 5MB PDF (Figure 47 - page 73) - Supplemental Material See Usage Policy. 6MB Repository Staff Only: item control page

U 1 VES'l'IGATIO'N OF THR lNSTAl:tTntEOUS VF..LOCITY orsTHIBUTIOM IN Tlfr.. VOLUTE OF CENTRIFUGAL PUMP Thesis by Ra}ffl'lond c. Binder In Partial Fulfillment or t he He quirements ror the Degree of Doctor or • h1losophy Ca.11f'orn1£•. Institute or '.I1e chnclogy , Pae a den , California , 1936 suw· RX A 1H~ohn1 que was d . velopod for mea suring the in t&nt neous V6loc1ty v otors in the volute or a centrifugal pump . The d velopment r sulted in thr e ma jor in trum nts- a op eie.l Pi.tot t 1be ; a a peoial diff r nt1o.l gago , ltnd n s mp 1.ng valve . The c.urrerent1a l eage ia s m:: ny e.dvantag(!ts over the pecia l rdin r y t., e of di , feren 1al gage .• a nd m e ma ny oth r a ppl1ca tions be id.es the one in t l'11 s t udy. Experimental ch eck s hav& d mon tra ed .he r 11ab111 t y of th1.e new technique of iriea sur ment . Rxtensivft measurements w r-e made onto high ffio 1enoy of C01!i'll'lfflro 16l design , one a. double ucti on a nd een tri f'uga.1 pump t other a a 1ngle u otlon type . P1t ot t a t1.ona er rov ided r ound th• entire v olute of' the single suction pump . Test on thes e pumps showed t he fol ov11ng: l) Thero v.rae ;,r.,, otio lly no ina ta neous velooi ty V Ei :r1a t on betv;een vanes at nor l pump e paoi t . There was e s l i ght var1.a t1on n t lo·l'f and hig 1 pump capacities . 2)'?here was e positive radia l veloe1ty outside t he s hroud in n•arly a ll ca ea at normal pum eapae1ty . 3) Some double pea~ed ndial volooi ty profi • ee were obta ined in tra verses a cross the vo l ute a t lo p-ump dischar ge . The most rea s onable ex 1.~ns tion st tea the.t tbeae peaks were due to the centr1.t'uge a ction of the shroud . 4)The single aucti on pump test s howed considerable inflow at the volute tongue I t hat i s , fl ow towa r ds the com letely ump elm rt cross the volute . 5 )At low • normal , and high diee r gea the flow c oncU tione were not tmiform around the voi ute . 6 )The fl ow conditions a t nor mal o pe.eity w•:re more uniform t han a t low and high capacities . 7)There were two unba l anced r e.dial roreee ne ting on th«? impeller , o. sta tic re st,nt:re force a nd force . The momentum forc e was sma ll unbalanced sto. t1e pressure fore&.. u1 momentum c ompar ed v.•1 t h the f! he writ r expres es his deep appreciation to t hose 1ho b.e. v a ided in this inv@at:lga ticn . Prof .. R . T . Knapp ha a Jc1ndl .r gi ven a dvi e ~ and ''mlp th1"oughout this lengtl y tasl< , and Prof . ~ / ,on Ke rman hae helped toivru~ru;i explaining some of t h e 1 esu ts . a teful to the Metropolitan Water Dietriet of Southern California in many respects ... :for- the u e or tb.e pump laboratory nt th District's expense ,. for paying ?or the epecia l appa1~ti tu.a , for hel 1n some cal cu l a ting and some plotting ::>f t he results , and for permission to use t1e experim ntal The vrri ter is very ,,,r a teful to the Byron Jaekso:n Pump Jo . a.nd the Wo1~thington 1-'ump and !.la. ch . Co . for permission t o use the results of tests on thei1"' pump s . 'I'he Byron Jackson Co . through I. ts Chie f" Engine01· , Mr . A . Hollande:r·, and the Worthington .Pump and. 1~0. c .. Co . b.roug.'1 its Chief Engineer , Mr . M. Spillmtt n , ha ve k l ndly INTHC.)DUOTION • • ••• • .. • • • • •••• • • .• • • • • •• • • • •• • • • • • • • • • • • • • • • .. • • • f Object ot Investigation.................................. 4 General Method ••••••• • •• • • •••• • •. •. • • • • •·• .. • • • • • • • • • •"' • • • • • 4 PART ONJ:i:--TEOHNlQU'I.£ OF M.F~StJREktHNT • •. • • • • • • • • • • • • • • • • " • , • • • • • The P1 tot Tube Wett sureme:n t • •••••••• • • • ••• • • • •• • •• • • •.• • • • Pi tot ~rube Wall Correo tion. •. • • ••• • •. •. • ... • • •. , • • ••••• • •• • S tuf'f1.ng Boxe-s in Volute • ••• • •••• • • •••• • •.•• • ••••• • • •• • •• • Spees.al D1ffe1•ent1al Gage .• ••••••••• •• •• ••••.•••••• •• ,••• Sa:mpl 1ng Valv-e and Phase Shifter ••••••••• • ••••••••••• •••. 6 6 12 12 16 22 31 General Remar ks on Teclmique .of M&asurement •••••••••••• • • 1 1 PART TWO- 'fl~8'1 RESUL ?8 • • • • • • • • • • ,. • • • • • • • • • • • • • • • • .. • • • • • • • • • • Notation Used in Measurern.ents .................... ~••••••••• 33 33 Instantaneous Veloe1 ty Metl.surements on Byr,ion J~ckson 8" Double .Suction Centrifugal Pump ......... Pump :Ra ting t1nd Dimensions ........................ •.• 34 34 Instantaneous Velocity Distribution Between Vanes .... 36 Velocity Traverses Across Volute- Eff'eot of' Shroud on Velocity Dist:r•1butto11,..... • ••• •. • Pi tot 'l"ub0 Measurements at D1ff~rent Pump Disebnrg ea, • .• ••••••• • •. • ••••• • •. • .. • , • , •• • • • • Comparison w1 th Mom.~ tuni Law ••••••••••••• , •••••• • •.• • !nsta.n t8.n~ou-s Veloei ty P.~,aeu,rements on W1orth1ngton 41 48 4s . Si1-agle Suction Pum1h • •••• •. • •• • • • • • • • • • • 5'1 Pump .Hating and Dim~ns i ons ••• ,. ••••••• , •••••••••• • • • • 51 l nstflntanE>ou.a V@looi ty Dietri bution Between Vanes •• • 53 Velocs. ty Tr av~r~HH~ Across Volute 'f' A) Normal Pump CapacitY•••••••••••••••••••••••• 60 B) t ow l'ump Cs.pac1 cy •••••• • •••••••••••••• • •• • • • 61 0) High Pump Capac1tY•••••••••••••••••••••••••• 63 Unbalanced Radi al 1~lo1"ees Acting on Impel l er......... 64 Powei- Balo.nae Irround Volute ••••••• • ••,•••••••• • ••• •. • 65 Direction of Velocity Vectors....................... 7,9'; 3ibliography •................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 IND • OF FIGURES FI GURE PAGE 1-Di ngr am of General method ........... . .. ........ ...... ... . .,. .5 2-P1tot Static Pressure 'ee.surement ......................... . 6 3 - Construc:t:i.on of Special Pi tot 'fu.be ........................ . 9 4 - App.ara. tus for Cheeking Pi tot Tt1.bes ......... ,. ............... . 1 1 5 - Pi tot 'l'ube ir rave.rs:es .i\cr-oss Brass Tub~s ............... ., ••• 13 6-Pi tot Tube V-lall Correction .................. .. ., .... . ..... . 14 7-Methorls of Inserting Fi tot ·rube i n :; ump Volutes ........... . 15 8-Speeial Diff'erentlm.1 Gage ............ .• ...................... .. 17 9 - Photogr aph of Spec ial Differentia l {sage ••••.••••. .• • • ••• 19 10-Photog raph or Special Di f f'erential Gage .............. ., ...... . .20 11-1:'ialibra tion CU:rv , of Bp~c:i.a.l Differ0ntial Gag e .............. . 21 l2•G~nera l rrangement of pp6.ra tu~ .............. . .... ...... . 23 13•Conetruct1.on of' Slid~ Va.J..v·e ............ ..................... . .. 2 5 14- 1"> lot of Valve Velooi ty vs . Va lve Poai tion •.•••••.• it ..... . 24 15- Appe.ra tus on Wor t hington P mnp ... . ........... ... . ,. ••••••••• 27 16• .ilppar a tus on h orthing·ton Pump ........................... . . . 28 1? - A p pa r a t.us on llyron Js o-ks on Pump .... . ............... ,. ••••• 29 1-8-Ap pa.r e tus on Byron Jackson Pump ............................ ... . . 30 19-Nota. tion l1aed in Measurements •. •.••• , ...... . ....• ,. ...... . . .. 33 DYRON J ACKSON PUMP L.EAStlRG.OO !r'.t, ·rs 20- Spac:tng of Pi tot Sta ticms in Byron Ja ckson Pump •• .•••• •.• 35 21-Vane Space · A,baolute Veloc ity Di stribution, Pos . 12 ........ . 37 . 22- Va.ne Space : bsolute Velocity Distribution, Pos . 2 •.....•• 38 2S• Vtine Space :ibsolute Velocity Distributton, Pos . . 1 ......... . 39 24-Vane f:\pe.ce Rn. dial Veloclty Distribution ... ..... ..... ..... . 40 25- Velooi t y •rr a verses l! cross Volute ....................... . . . 42 26- Vt1looi t y 'l'r verses cr-oss Vol te ............................ . 43 27- Sketch of Volute Ca se with Small Clea.re.nee ... . .......... . 41 28-Sketch of Volute Ga:s(9 with i.anp le Clea.rane e ............ o ~ ~ •• 41 29-Disc Velocity Distr1butio:n..... ,. ................ ., ............. .. 45 30- V-e locity Vecto1•s at Poe . 2 .......................................... 47 31-Mea.surements at Dift>ei--ent Pump Discharges ..................... . 49 32-Compe rison 1v:l.t h '~omentun1 Law .......................... . ... ., 50 W01 'J:Il NG'l'O.N PUf1 P !NEASUREMT?NTS 33... s pa.cing of.' l l tot Stations in \'l orth in.g ton f ump ........... .. 52 34- Vtine Space Abaolut$ Velocity D1stribution, Normnl Q •••••• 54 35- VanE'! :-Space Radial Velo-c.i: t y Dtstr1butio:i, No1-roal Q......... . 55 36-Va.ne Spe.c~ ...i bsolute Velocity Distribution, Low Q......... • 56 37-V-ane Spae e Hnd i~l V~loe i t y Di str-ibution , lJow ,i ....... . ..... . 57 38-Vane Spa.ee Absolute Veloei ty Distr1bution, High t;_ ......... . 58 39-Vane Spaee Radial Vf}loci ty Distrib-ution, Hl gh c.2•••••••••• 59 40-Traverses Across Volute,. Normal Q. . . . . . . . . . . . . . . . . . . . . . . . . 66 41-Tr averses Across Volute , Normal Q ........................... ·• . 42- Avera.ge Radial Ve1oc1 ty vs. Ang le .Around. Volu ta , Norroo l 1, 43-'fraverses .A o:roas Volute, Low Q................................ . 4.4- Tra vei-•se-s Ae1~oss Volute-. Low ij .... . ........................ . 67 68 69 70 45-Avera ge Hadia.1 V~lo-c i t~.., vs. Angle Around Volute , Lo ., Q .. .. 71 46-Traverses .Across Volute., Hi gh Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 4?-rrr ev ersG~ Aer·oss Volute, High Q ............................ •. 7 3 48-Average ~d1al Veloei ty vs . Angle Around Volute ,.Hi gh Q •• 74 49- Sta.tic Pressure Di stri.bution Around Volute ••.•.•.•••.•.• 75 50- Unbalaneed Radial Forces Acting on lmpeller ............... .. 76 51- Power Balance Ar ·ound Volute ................................ . .77 F!Gt1RB 52 ... m::i,t a tion Us~d 1n De~tgna.t ing Vector :()tr~ctiont1hu.... 78 53... Averag~ An gle, of £.1-bsa.1':..i.l.@ Velocity •• ~ ► • • • • • • • • • • • • . • 80 54 ... .Mrerage Angle o~ Relative Exit V~loeity .... , • ... • ••• 81 l INTRODUCTION There is need for more experimental data as to the flow conditions 1:n a centrifugal pump. Beoause of a la.ck of both qualitative and quantitative inf'ormat1on pump designers have been forced to speculate as to the flow character of the water 1n the impeller, volute, and other regions inside the pump . There is no doubt but wha t actual mea surement's on a stand.a.rd high e:fficienc-y volute pump would be of considerable interest to the pump designer and the student of hydrodynamics. As for previous work, theoretical studies or t he impeller flow have been ma.de by Kucharski, • 3 4 1* 5 Schultz, Sorenson, and Uehimaru and Kito. 2 BuseJllf:lnn, Ea.ch of these investigators assumed a perfect fluid and used the method 6 or potentia 1 theory. Pfleiderer ealeula ted the theoretical head developed by a pump with the condition that the relative 1 exit angle was less than the vane angle.. Kucharski treated mathematically the problem of a.n impeller with straight 7 radial vanes, assuming an ideal fluid. Spannhake pointed out that the rluid passages , formed by curved vanes of a rinite length and cut orf by entrance and exit circles, as found in actual practice, present many difficulties to theoretic-a l investlga tion . It is well known tha. t the s.ctua.l values of the absolute velocity (in direction and magnitude) do not agree with t he theoretical calcul ated values based on 8 potential flow. Fischer and Thoma concluded that "Praeticamy *Reference numbers refer to those in Bibliography a t end of' this report. 2 all flow condi tiona for an s.etool fluid are fundamentally different from those theoretically derivEld for an ideal frictionless fluid" . 9 Prof' . R . L . l)Q.ugherty h.."J. s ma de a combina t1on experimental e.nd theoretical ane.lyeis in his book "Centrifuga1 Pumpsn . or pt.irtieular interest is hie po in ting out tba t the vane engle and the a ctual rel&tive exit angle may differ by from five to t en degrees . Probably one of the first(if not the first) experiments to stu<iy the flow conditions inside a rotating hydraulie ooaehine was that of Franc1.s 10 (1851) . I n his test on a Tre ont turbine he inserted a w.u1e at the d ischarge of the ru..~er , which gave the d:trec tion. or the Wt\ ter let-lVing the wh:ettl . Q;unl1ts.tive photographic $Xper1ments have been made by a . 11 Fischer and 11homa 12 • Oertli 13 , Siass 12 • nd ot-he1--a . Oertli showed that the flow in a centrifuga l impeller 1s not exa ctly two dimensional . The work of Fischer ~nd ~'homa was extended by 14 phetogre.ph:ic experiments made by <.;J.oeterha lfen who used a pinnp r1i t h a transp . rent e e.se, and men sured the pres sure a t some points ilong the va nes . 11'.\ese photogr aphic 0 periments were made on special laboratory pumps specia lly prepar d ~op observation purposes . 'l 'he question has been raised a s to \ffi<➔ th r resu.1 ts from auoh ta technique ee.n be ~xtrapola ted t o a oonsiderE1- tiOJ;l of a pump :>f oonmeroia.l design . 15 Yendo us ed. pressure meusuring holes in the guide 1mnes of a turbine pu.'llp to ob in the slip coe fficient . This nethod does not g ive a measurement of the magnitude or the 3 absolute velocity. 16 '!'his year Kasai bas reported his Pi tot tube measurements in a special laboratory pump having a vortex chamber. His experiments were made from April, 1933 'to March, 1934. With the exception of Kasai, these experiments were ma.de at low speeds, and efficiencies we:re low. The question has been raised as to whether results from such a technique can be extended to a consideration of a pump of commercial design operating at normS1.l speeds. The work of this present investigation avoided the dift'ieulties of low speed laboratory models. A technique was developed to test a standard pump of eommereial design, and at a speed at which the maximum pwnp efficiency is reached. The present study was started in the fall of 1931 in the Hydraulics Laboratory of this L'l'lstitute. Instruments for measuring the average velocity vectors in the volute of a centri fugal pump were developed in 1932 by the present author working with the help and advice or- Prof . R. T. Knapp. 17 An M. S . thesls in May, 1933 described this technique. At that time (1933) publication of that work was held up in order to extend the technique, to improve instruments, and to wait to do t..'h.e work i n the new preeision laboratory then being constructed at the Institute under a co.operative agreement with the Me tropol 1 tan Wa t&r District. 4 OBJECT OF INVESTIGATION The previous experimental investigations have had some limitations and restrictions which this investigation sought to overcome. This present study extends this pa.rticu- lar field of experimental knowledge and technique in the following significant respects: 1. A technique of measurement was developed to test a standard high efficiency volute pump of commercial design,. thus avoiding the difficulties cf speeial laboratory models . 2. Besides developing an improved technj_que for measuring average velocity vectors at a point in the volute, a technique w2.s developed for measuring the 11 instantaneous" velocity vectors at a point in the volute,. that is ., the velocity for a time corresponding to five degrees rotation of the impeller. 3. Very extensive measurements were me.de at closely spaeed stations completely around the volute,. using both the naverage 11 and the· 11 instantaneous11 velocity teehniques. Complete sets of data were taken for different operating eondit·ions, varying from nee.r shutoff,. thr_o ugh normal tto high rates of discharge. With this expe1.. imental information it has bee-n possible to analyze (a) the comple te velocity distribution of the flow between the i mpeller and the volute, and (b) the variation in the velocity distribution in the dis charge from any one impeller passage . GENERAL METHOD Briefly stated, the method employed was to insert a 5 special P:i.tot tube across the volute. Referring to Fig. 1, a sampling slide valve was inserted in each of the two connections from the Pitot tube to the special differential gage . ' I, • 5P£Ci r1J.. lJ1rFE,e£NTl/1L G~GE Vt9LV£ IMPELLEI? These slide valves opened for a short interval of time ea.eh revolution of the pump, which resulted in a series of pressUPe impulses to the gage . Means were provided. for shifting the phase between the pump shaft and the va lve opening. scope indicated the position of the opening. A strobo- 'I'hus the velocity eould be measured as any particular point of the impeller passed the Pitot tube. In these tests, all the facilities of the I!ietropoli tan Water District pump laboratory at the California Institute of' Technology were employed. The automatic speed control was used, and aecu~ate measurements of' pump head, quantity, torque, etc~ were made simultaneously with the internal velocity measure ments . This report is divided into two parts . Part One, describes the technique of measurement, and treats sepa.rate,ly each major instrument. Part Tv10 gives the information obtain- ed f'rom volute surveys of two different pumps . 6 In any flow measurement it is not diffieult to determine the t1~ue total head or dynamic pressure. The total hEulld. is obt.i:tined by placing an openi.ng norm.al to the d1.reot.h m of flow . Since the total pressure s ,uals the static pressure 'l'he ma.in .f eature of the Pi tot tube used in thts study is that bulent flow .. Tl is ae<Hl:rSi te r.1es.surement can be seen by eousidt!rlng the pressure distribution around & sma 11 oylind.ar a.eras$ the stream . Referring to Fig . 2 , it is lmown that the1•0 is a cri tieal ungl e with the direction of flow at which the velocity pressure ti.es no effGct . 'fhis means that , ho.v:Ing 11n opening at the er:i.ttenl ~ngle with the fl ow direction, the /?xis or CYLINDER/lc,eoss 5 T,€E/JM riG-.. 2 7 pressure transm1. tted to a gaga will be t:ru.ly static i.md. \L.~e.ffee ted by any influence of vel ocity. Ve.rtous investi ga tors l'la. v e found the va lue of this er1tieal angle. 18 The rough measuroments of Dryden indicated that the angle was slightly le.a s tha.n forty degrees. ·r echheimer made very ee.roful mea sureme nts with 3/16n and 1/4~ diamGter• cylinders in a stream of 111.r and found the e1":i.ticti.1 angl e to be 39:t degrees . In 1926 Dryden, n,oss, and other aut horities agreed ti:-..a t I~echheimer' s determination gflve a. means for the most accurate measuret00n t of static priHHmre in turbulent flow . 'f'he author has ch eek0d th'.is crlti.c.siJ s.ngle and the eonstruetinn of l/4n and 3/16" diameter Pi t ot tubes by observlng th0 position of t.'11.e hole in a stre~1m of' known diNH}'M.on a.t a po:tnt ~,he.re the stta.tie pr0ssuret we.a known . rh1s c heek 1 gave an angle of 39·¼ degrees f' or the ve loe i ty r ange met :tn t hese pump tests . It is interesting to 11ote that these la tt.er measurements wer e raa de in we ter., but t ha t the Reynolds t nwnber was s ubs tan'tially the s ame r11. s th.qt uaed by Feehheimar . A sta tte p:res~ure eomparisc.:m was rna.de on a pump pro- vided with several pressure e onr1eetions in the volute wall . 'i1be pressure at e a ch wall point was mefHtur$d wi t h the lo.bor.. t ory ba lti!.nce pressure gages .. Pi tot tube hole s were a1 so drilled f.n•otmd the volute H, .nc s t."J. ti.c pr0ssur e s m@t.;1Su1•ed with a. Pi tot tube built on the bm.s1.s of this 39¼ degr(irt?s idea • ___ _______________ . ..... , ,,. - ...... ------•- ---·· 18 .. u Ai r Force$ on Circulta r Cy1:tnders", H ••." . Dryden , 3c1er1tific Pa.per No . 394 , i3u?"eau of 8 t f:.. n da rds, 1 02 0 . 19• .1L.G. M. E . Transactions,. 19261' Vol. 48 . 19 8 closely, t..ri.is e'l'-seking the l' :itot tube . An exact c omparison was not possi ble because the Pi tot tube holes were s lightly di s .. placed in b oth r adial and a xial di:r-ections f rom t hoe stat i c pressu.:t"e connections :in. the volute . Fig . 3 ( Ps.ge g J shows the eons,true ti on of the f> l tot tube. The s 1nall pressure openings i'ltere po ss ible becaus e of the use of especial differential gag~ (described on Page 16)• In using the tube 5.n the pump volute it waa necessary to '' bsl1:mce 11 the tube . Two static holes wer~ used.,, ea.eh hole being c on .. neet~d to one side of fl differential gage . The Pi tot tube in t he unknmm st1•eam was rotatod about its own a xis until t he pressures at eacb hole were t he s ame , in other 't'l!Ords, t h e differenti,"1. 1 p:r-essure wn.s zero . At t h is position velocity pressurEil hs,d no effect on either hole ,. and either hole could be used to me a sure st&ti e prossm:~e .. The e:tsector o f t h e angle between the holes ga\m the direetion of flow . Tbe dynamic pressure was t hen obtained b y pla.oing en ope11ing normal to the direction of flow , i .e., b y simply r.ota tir.g one hole baek into trie stream 39¼ degrees . Thus, wi t h the v1.:t lues of the dtreetly measured tota l and sta t i c heads , the difference gave the ve loeity he ad, an d the me a sured e.ngle ga ,,e the d1reeti.on of the valoc 1ty vector. I n orcler to insure that the press ure c,penings f aced up stream t he Fitot tube waa ftrst rota.ted 360 degrees to f i nd the approxinm te p osition fer maximum p ositi.ve d:yni!11.Jte pl "EH:lsure . Then the direction wa s more aceurn. tely deter. :l.ned b y 0 ba1ane ingn the pressures . A. Pi tot dil:imet@r of 1/4'~ wa s the sma llest th~. t .see.med ,,~ 5E~Mi.ES5 BR/t.5.5 TvBE :::: FIG. 3 Prror TvaE 5oLDEJZ P.LvG- BErwEEN 1101.E.s SPEc1nL 8.11,eJ:11£12 ?os1TIYE LE/1¥1'.eoor s If No..eM/ti. JI lJR11.LED /1ccu,e,qr£LY SECTION f"l-11 t'VV °-;;~ To /lx1.s OF Tv8E PNo 1N THE s~M£ ?LRNE Nor£: Hot..E.s ,, 0.040/ioLE .,cp s a fe. 10 lt probably would have been desirable to u s e a mm lle1~ di t1r1w ter bu t, at _ t he ti e t his V.O l"k wns 1.nitia ted brass t •1bing wa s th0 on.ly rnateriB.1 aviila.bJ.e . It was felt t ha t the htgh ve loeity pressures eneountered might lw. v0 caused an a.ppreciable defle ct ion of a s maller tube. Fig . 4 ( Page 11} shows the nppa.r•s. tus used for cheekix1g Pi t ot tubes. Th e s wing s-pout and vol um:e mea s u.1.. lng tank m&de possible a. mea surement of the total r ~1 te or flow, wh ile the lorg leng th of pipe before the jet at:rs.i gh tened o-ut the fl ow to insure a.o curacy of di r e ction . The jet diameter WA S mea.suy,ed v1 th a. s peci.a l micrt1me ter jlg . Wi th the Pi.tot tube in the free jet va rtous tests were ma.de on the magnitude of velocity me11 surement. These a r•e t ~.bala ted tn rrable 1 . The sma.1 1 d ise.r e pane:i.es are due to the jet setup itself. Table 1. Ch ecks on Magnitude of V'eloc ity as Indicated b ;.· .Pi tot t.rube . Actual Veloe 1. ty Velocity Indica ted (in Free Jet) 26.6" - -·· 3'7 .o Pitot Tube 26 .6 37.0 41 . 6 45.1 48 . 4 53 . 0 41 . 5 45.1 48 .4 52 . 9 Feet per Second 55 . 0 517 . 2 by 54 . 9 57 . 2 11 1 3 'PIPE-/18011r 20 D1~METE12s LENGT1r BFrORE NozzLE BJ?fiss Nozz LE-/ "01r1. Vo1..VM£ M£11sv~1NG HIN):; nG, 4 D1/iG.£~M OF l'lPPRR.ltTl/5 Fo,e C HECK I NG P!ror Tua£s 12 PITOT . 'NJ~- WALL .COR HRCTION i""or pump traverses a oorrecM.on has to be a·ppli. ed to compensate for the c102e proximity of too Wt:l ll . Using 11 t.he appar a tus shown in Fig. 4 ,( Fage1t J, 3/l6u tu'ld 1/4 d i ame ter Pi tot tubes were in..~e.rted across dif'fe:i:~ent sizes of' bra ss t1.tt,es. Ve:J.ocity trav~rs es were nnde us ing the same technique as on purup traverses.. !tig. 5 (P~ge 13, shows some of these Pl'"Ofiles . For each ease of a J:'i tot tube in a pipe the mean ve loci ty from a tl"averse was comp,ar&d with the mean vel ocity fr om s .i Mul ti~ ecrus volume mea surements. 'il>t11s plot :ts shown in Pig . 6 ( Pa ge 14 J, and oovers mor e than the range met in pump traverses . Fig . 7 (Page 15, shows how the Pitot was inserted tn the dif f'er.ent pump volr.1·tt>S . l.ong stuffi:n:r.; boxes to give e r igld i~upport t.o the f :. tot tu.be . V<i'I.:H'"G used ! !I .. I ! . _J .. . ··+-- •i •• i . .:-~I···· •: t .._: ' •• [: 1 z ; ! I ' : I --:• ,__-~ :i. I I i I I ... _: --~ II - - - - -- • I ! ~ ·· !-··. _!I ___ -· ·-··- · ! L (- : : j ' -,' '-C~ c - - ,- - - t ·t :. ·+-Ii-- ---r-·1· : .· .••;< . !• -; ··-:-_r-- --- ·- :,-r~ .I - •i - -' j jb, •1•-~ -·----:-: ·-·· --· 1 - - - ~ - ------ - - ·-------~ - - - - -- ----····~ - 1--- -·:~--• -- -·--!· · ___ tl_ __ -· i .. i .. ! •. - . I . 'Ji~ i.: i -· , ~- - : • . ,i 0 ~ J I __ •.. .. I ' . :-:· -. .. . ' I ) . · _ . -~ I ' I . •• ! I j I 1--~--- l ' 14: / 0 .:. u . .. - 15 ~IMPELLER R.40/AL SECTION TiiRu o,=- 511-111../JR VOLUTE BYRON J11cK.SoN DouBLE SvcnoN Pu11P SrvFr1N6- 8ox ON Or lloLuT£ OTHER S1D£ IMP£ 1..1. E R. R110111L oF .51NGLE r/G-. 7 SvcT/ON METHODS Tu8£ IN S£cnoN THR u VoL v T £ WoRTHING TON oF /NSE R TING D1F F£R EN T P v •"fP Puf'1 p P1ro r VoL U T E S SPECIAL DIFPEHEWi:IAL 0-AGR -- -·-- ------·- be out <.>f t he questi<. n on. t hese f 1uctua t i ng pr r~ ss u1"e mea s ur ements .. < ea di ng 1n a s ystem us i ng nn ordino. r :,r U t 1 .be a n To obta i n a ap ~r>P-c ia le flo.1 1 s 1·•equir•ed t rn:~ou _,h the Pi t ot presr.n1.re opening s and tho c onn ect:tng l eads, he n ce a reedt ng cou ld n ot be obt r; :tne d in n r•en s ona l o t i me. Thi s di ft t cul t y was over·c ome by the dovelonmc-mt of a spec i a l d:Jf:ferential ~,ra ge. are t ha t on :r Its rtf\5.n f<~£-. t ures very em·ll amount of' f 1ow i s r ~qui:red for operAtion, the gage ts ve 'Y res p ons:lve,. sens i.tive, an.r S1. oeurt1. te. ~..an e xp<n ·i ·enter s us:trig Pl tot tubes have been l :i.m:t t ed by t .1e uso of U tube manome ters. Buch a rr.cinometer •pequ :i res t ha t the P :I tot pressure o penings be 1£u?ge enough t o avoid excessive dnmp iri.g, while t h is speciHl dtff'erential ga 6 e permits the u:se of much s maller pressure op nings. Fi g . 8 ( Po.ge 17 ) shows the inter-n a.l eonsti· iction. Si nce t h e helix elen1ent i s the Bf.H!l{t a s 1e u.sed on pressu re r e cor d - ing ins t1·uments this di fferenti.al ga g e e an be a da p ted to any deslred acctn•a.e y tm d r a ng e of pressure by e. suitable selec t ion of helix . One end of the helix eletrnent is fixed , while the other end is free to move. The free end is so connected as to ea.use a ·r otation of the stall :i tA mirror wh.en the free end n.oves . Water pressure i.s appl led t;o both the inside an d t.he: outs5.de of t he Bourdon element, t he whol e mechtm~~rm heir~ .i.n wn te:i: in o. el f>sed ea se. Thus, when th~ differEmtial pres sure changes,. the free end of the Bourdon element rotates the mirror.. The mirror arrangement ma.gniftes th:'ls mo venant with the aid of an optical Cr1sc BovRDON To To Cr1s£ PR £~SURE MIRROR 11~.. .~ Ror/{TE.5 OPENING FREE END · l'lvor ,4.eM- MoVEM£NT rREE END oF IIEL1x rixEo ELEMENT HELIX nxEo To V/15 END or HELi>< I I ►k ST/llNL£5.5 To INSIDE ?1?£551./RE STEEL ,P;vor.5 '5PECl;:?L D1rrE,€ENTIRL GfiGE .5iELL/TE M1R-RO,€ GL/?55 WINDOW F8:j OF HELIX OPENING ~· .q: 18 ayste,:m . A light sourc-e sends a beam of 1ight through the glass windov, to strike t'm mtr:r.-or . a grl¼ du~ t~d t.Hml~. 1'1e reflected rr:i,y was focu:sH:Mi on Some photogrtt.phs a.1:•e shown in 'F1g. 9 and 10 ( ?ages 19 s.nd ·20J .. One interest:in.g problem wns th£ t of the eh:roma t'ie dispers'ic>n of the li.ght irn&:tge.. Betwee-n th~ glass w:l:ndow and the mirror is a var1.s.b1e prifnrt of water . Vlil r:i.ou,s :mo110 -elironm tto. lamps W'EH"e t'rted, l)ut proved imsa tis fn.e toey .. '11tl e most :sa tts - f 1:;1.ctory solution ws. s obt$it :in~d hy simply :l.n1Serting e. l i.ght f'ilter d1rectly :ln front ot the lamp . The gage W®S ee.lib1~a.ted i•dth a det\d wetg ht giig e te-ater. Fig . 11 {Page 21) shows a typical ::itl"aight 1in9 calib:ra t.i<~n e1.u:•ve. Hepented tests over J.ong periods of' time- ha.Viii sho""m that t his gtl ge h olds its et!l. libr~tion pree :isely . Onf:: faet,or th.et might account for thia iti that of the nelectton of tb0 helix . The working prea,sure range of tb~ b,o·li:x element is about one - third the rated pr$SSu.r-e rtitn(;e;e . By re. ted pressuro 1•smge is m(l)ant the rang~ of the helix element as us0,d 1n standard :rec◊T--d ­ tng inst'I"!,,Hnents. ;feats h.~.v~:i ~1.own that the, seal~ def1eeti.on depends so1el;f on the di ff(i;!'et1t5.!:l1 p:t' $filS11r0 .. ti nd is 1.:ndependent of the absolute pres~ure .. 0:ne 1.n.t erasttng fee.tt.u~0 of thHi gHge is that it requires no time to give a prinJsure remdtng . If the eooks (oue to a.l ose off one eonri@-e tion from the Pitot tube , !B!:nd the other to open the vent) ru~~ handled qui ckly the lif.,h t image comes to the pr©ssur~ posi.tion q_u.'.icker t han the eye can follow it . In this gage there ie no e,pprecia:bl~ flow of wat~r ., it :ls pr•acti caJ.ly a. eonstnnt volume system . It ts obvious the. t man y other appliea- tions e .s.n he found for t his type of pressure 1.nstp1.~nt . 19 ) 20 Fi&. /0 ) --1- _ 1l----:-1 : - -·-····-·-L---- - i • :i j~ ' ' • - -- - ' : ! - • ' - - 1____ - - - . ' -· • ' - ....... L.... . _____ ; ·_ -· ! 22 SAMPLlMG VALVE AN D Pfi,, SE SH IFTER With t.li.f.:l P itot tube a nd t h e s pecit.11 dif'fe:.renti a l g go, measurements or average v e1o.c 1ty et-.1.n be made in. the pump volute. Dees.use of the minute flow required to opera.ta the dtffe.rentio.l gage it was possible to use a slide valv~ to sample the pN>Sf:n.,re tra nsmitted from t he P:ttot a s &n·y particular point on the i mpeller f.lS. SS~d tre Pitot tube ,, A deseript lon foll owed by s ome photo- g r aphs wi 11 show how t.h is was aecomplish~d . Fig .. 12 ( Pa ge 23) showa t h e g {!}nera1 e.rrs.ngernent .. 1'he two pole genera t9r on t he dym•Ht.l.ometer shaft drove the f~our pol~ s ·y nehronoui; motor at one - half pump s pe ed. A.n eeeentr:i.e on thG rJioto:r shaft worked in o. yolre to i mpart shnple liarmonie rnoti.on t-o the push rod driving the t wo valves.. Each valve op0ned twice (back and forth) i"'or e veI·y i-•evolution of the synchr·ono·U:s motor, which ecant one valve open i.n g per r(->V◊lution or the pump . W'h.e.n the valves oi wm0(l the comi,ute.tor eor1tact would fire the neon light at the protractor on the pur11p shaft (one fir5.ng per one revoh1tion of pump).. The bol ts between thR fi0ld and t h e end bells of the motor were removed , an( mcrnns provided f~)r rotat i ng the f1.eld of the motor., '?l1us there waa a r,os :U~ i ve m0ohnnle al - eJeetrie a l connection betwe{f.n t h e pump sha ft a m . the slide valve, and by simp l y r ot 3. ting t h e field of the motor it was po ssible to ch an ge tho pht1 se r•elat:1on between the p:urap sha ft a nd the ttma of opening of the ve l ve. lt was possj_b1e to c hange the pha se by 360 degree s , whi1s t he stroboscope alwa ys gave a precise indie£it1on o:f the position of openjng, of' the valve . PuMP St111Fr NEON LIGHT- ON P12or1u1c. ro,e ,l' '<J ('oft ~.l' oN -----~--· .5HIJrT fl£ £/tNGEMENT OF ...., VN1T ►---- fiPPl1R/1 TI/S Pow£ ..e .5 TRO 8 0.SC CPI! r!El..l) Moro,e- Mov/18L£ ..5 YNCHIZONOU.S J)yNl1M"METEIZ- GeNE!e/lroll to V/IL.VE Pv.511 Roo ---r.1~,..,1 Roo BETWE.eN V,t,1.v.t:s CONNECrtM, _ _ _ _ _ _ __ _ _ _ _ _ _ _ __ HG. /2 .___ _ _ __ PvMP VOLUTE Prror IN C oNTRc r Is Is n12E1J RT PRoT~flCTOR W;;EN CoMMVTRTOR. t=°LYWHEEJ.. G/16£ D1f'FE££/'IT/RL t\) : tN 24 Fig. 13 (Page 25) shows a self'-explanato-ry sketch -o r 20 one or the valves. Mr. :~ . R .. Lockhart h elped work 01.it the details of tm sampling w 1ves.. Both va.lves are d.~ pltcH.t~s, and aceurntely positioned to open et exnctly the ss.t1e time. Use was md.e of the fa.et t~.1.t the eeeentri.c t-tnd yoke 1mpart~d simple ha.rmon1.e moti.on to the v~tl.ve. Hees.1.ling the curve, Fig . 14, s.t the middle of the valve travel the ve1ocl. ty set to open at the middle nf' tlH~ t?"avel. W1 th n slot thickness of O.005" the time of' opening eorres9onded to nn angular rota ti.on of five degrees of the impeller. Por the present e. shorter tinte ?os1T1cJN OF J/17L VE' OPENING 1---VRLVE T.eRVEL----;;o~I FIG-. 14 or op,e ning was not or grea. t interest. The inert:in forces of th0 reciprocating parts wer~ reduced ns much as possible. Operating tlB motor nt one-half pwnp speed helped do tbJs. Each slide valve was placed ln a line from e. dead weight gage tester to the .s peein.l different:1.al gH.ge . As various known pressures were applied the corresponding dit"ferential gage -----· --- ---·. ....... 20. IDl . S . Thesi.s ll . R. LoekhHrt, 1934. MDTH Or CONSTRUCT/ON SJ..or-= o.oos'' Si.10/NG VRLVE, /1&. /3 IIRL V£ CcNN£CrJN6- To 1)vPuc11r£ Rt:>D PoLI.SHED t,,r101u y rLRT VRL V£ .5£,9T ON ---PRESSURE VRLVE OF By SLIDE V11LVE OvTLET SERT r£J:?ME HoLDING 5Ltl)E o.oos" WiDE SLor VliLV~ SER, IN INLET PRE.SSV;.!£ }3y £ccENTl2Jc RoD Pus1r£0 Bnc,1e I ro.e TH Cl' Ki 26 readings were noted. at a ny speed is I t wa s found that the iotion of the va ve d. no e.ft'e c ro e 1- d 1e to t of 2.ero e.ecele1.. r1. tion. on t e pressure gage re~ d:t.ng . ft, ct, Th:ls h . t the val ve op(·m e at the point Whether oi-· not thts is t he comple te 1 o ha.s no ef'. ct on the pressure trr. nsm j t ted. An ot er inte:t•esti.n r; che c k vms made . insta lled on e. "ii t h ·he ap, re tus u.mp, in place of the Pitot tub e a n oscillating press ll"e or kno-wn frequEinc.~y wns app11ad to the sl i d~ v J.ve . The w run t a ri ous speeds a ch different from t he known fre qu ency of tr: e ap _15.ed :11•essure. For e a. eh ease t h e n ber of nbet?. ts" per minute , a s s r,_.ei n by the d. ifferan ti 1 g g e, c orr,~sponded exactly t.o . t 1e difference betwe en the pump R. P. M. lil nd th e eycJes per minut0 of the applied i,. ressure . Tests have shO!.l'Jn t ha t en eb sl 1d.o v a 1 ve when c l c>sed does not l eak . I f a gr 9. duelly dee:ree sing o:r inoree. . ng pres sure is a.pp J.:i.ed to H moving J ve t he d'- fferenti l r e ding changes in jerky steps - for pa1•t o g ge the time t he valve is c l s ed and the pre ssure reHding i.s he1d c onstr,;i_ nt. Sol'!le photogr aphs of instD.lla tions on t wo d ifferent pumps r e s ~<>lim in Fig . 15, 1(-; , 1'7 and 18 ( p,m.ge ... '2 '7, 28, 29 and ·30, . " ,.. rlG. 15 APPJ.RATUS ON WORTHINGTON SINGLE SUCTION PUUP PITOT TUBE WITH POINTER AND PROTRACTOR SYNCHRONOUS MO'I'OR SLIDE VALVE ~ -.:l - FIG-. 16 APPARATUS ON f.ORTRINGTON_ SINGLE SUCTION PUMP DIFFERENTIAL GAGE - ' BLACK BOX UNDER DIFFERENTIAL GAGE IS STROBOSCOPE POWER SUPPLY - tv CD - SLIDE VALVE Fi&./7 APPARATUS ON BYRON-J.(I.CKSON DOUBLE SUCTION PUMI' PROTRACTOR ON PUMP SHAFT - - - - - MECHANIS1l FOR ROTATING FIELD OF SYNCHRONOUS MOTOR tO l:O • " rtG-. 18 APPARA'I'US ON BYRON-JACKSON DOUI3l:.E SUCTION PUr.'P - C>l 0 31 GEffiRAL REM!;, Rf~S 01! JJ:EgHNli.~UB OF ~K 1\$UR 1t;MlfflT This technique or insta.ntaneous vel ocity m~atwewnt is pos.,ible bees.use t he s.ysten1 from Pitot tu'bo t o gage hns no volume changes ,. the pressure is tra nsmitted by the water with - out any flow .. Pressure wo. ves 1n the conmoting l ~ads mi gh t cause trouble" but the len g th or th e le.ads was reduced t o e, minimum by pl a c ing the sli de v ~l ve a s c lose a s possible to t he pump . As for aoeu.mcy of meastwements, the magnitude of v elocity was determined to w1 t h ln one - haJ. f per cent. angle wa.s 1.. ead t o wi thin one - fourth de gree . hil e t he ;..{any reodings WE!>re duplicated cl oser tl'lan thi.s . Tc illustrHte the sensttiv.ity of t hi s ap. -'Sr :1. tu.s a ca se wi11 be cited. With t he th1.~ott1 e ~ ni s uction head n t one setting the pump wr.;1.e opern ted wlt hout using the automati c s peecl control . 0 he s peed cou ld not va r y v,;rry much, no noticea ble wanderingti of tb~ v ent uri :ree. d:l ng or 1;he head (d eveloped by pump } read in g could be observed . However-, the internnl veloe i ty instruments shoiived en a:pp:rec ieb1 e "wanderi ng" or f' scatter"' of read1.n gs, the appti r a tus being sens 1. ti.Ve enough to d@ teot the slig ht vnr iations of t h e veJ.oeit y ve c tors i ns'.i.de the ump . Pu.mp tra verses ware made with caution a.nd conti.nuou.s ?"0ch~ irs to avoid any trouble of t his kind. . ! t is to be noted tm t all the instruments weN o r-e ... fully doslgned, e.m wha t ie re ported here is t he result o f c ons :l.derabl e deve lopr,1:ent work. The e xperimet1ta.1 eh eo ks ha.ve b een 32 mentioned. Test results lnve shown other checks .. All 'these facts demonetrnte the reliability of thi.fJ new teer nique of meiu,ur~ment.. The following se-,etion i:1i l l present t 1:ie :results or rooaauremm.ts on two hig.h efficiency pumps . one a single suction and the other e double sm~tion type . 33 P~RT TWO- TEST RESULTS For designating valve opening , on9 vane tip edge waa chosen as a zero reference . Fig . 19 shows for two examples the position of the impii'!ller \\'hen the va.lv~ opens. If the valve opened as the zer•o :reference mark passed the P1to·t tube the '' pha se angle~ \va.s •1 zero degr~h)S'1 • lf the valve opened as some other point on the impeller passed the Pi tot tube this poir1t was referred to the zero mark as so many H degre10s phase angl Jt,. where this angle is m.ea.sur&d in the opposite sense to th.at or th$ purt1p rota. tion, t . e . , the point t 1 l!!gs" the zer-o referenee . nG. 19 For designating the ax1.a.1 position of mea surement across the volute •~ center" m@ns ov@r the center or the impeller, v.•htl.e ft1-.1ght" or nleft" refers to the side from t his eenter. On the double suction pump u right" a.nd0 left" were used with the obaerveP f~cing the pump suction flange . On the single suction pump the "right" side refers to the suction side of the pump . 34 s~ri a l No . 128407 Type Double Suetion Cap,a city Total H~ad Speed. 2t,OO R. P . M.. 1400 . Impeller Outside Diameter 13 3/8" Impeller Inside Width 1 12/ 32° , l 13/S5i' Impeller Outside \lidth l 3/4/' Number or- Vanes 8 Al l pump tests we-re made> at 2000 n . P . M. The mx3.mum effieiency,(84.6 per cen.t) at 2000 R. P . M. wiut t'he ~ame as a t the ro. ted sp-ead. All t sts were made ~ t plus 40 ,,et inlet head . Fig . 20 ( P ge ;35) show$ the spacing of t he F' it.ot tube sta tions n the volute . R, /2 6 9 2 I 1Jt5TlrNCE ?trt>T CENTEi To IMPELLE/l. e 1JEG!e£E5 or P1r<>r HOLES II 7 "" ry '" I ,, I B ft,, 1"iin il ,, h '1'"',, I II ?vM p 5ucr10N s !PE Or 90.0 14~.7 2~. 3 II 37.8 3/e'' / .3" ,, 1¼'' / I/ ¾" 30.3 C 1..0CK,WI.S£ Z>l5TlrNCE (;ovN T E.€ Pos; TION I R1101Rt.. I 5PRCING- / MPELLE.R U.PP~R. 4 :512 £ Svcr;t:>N OF ? UMP 3 // D 1r1. =- 13 8 VRN£ E>ur /1N<i-L£-= 2 2.8° S I VE .1) l .5CHl'1RG--E Ptror ?os . No. ~ ?!ror ?o.s1rtoN No. I P,ror ?os1noN No. 2 OF VOLUTE H~u..,c ?vMP JRCKS al\/ r/(ir. 2.0 ScRt..E Dova1..1c BY-eO N ~ >-_,,,,.,a"' ~ ?lror ?os.No. 12 ~ 36 BE 1'WEEM VAitES 1 A very interesting question is that of t he instanta neous veloei ty distribution between vanes . To test this, mea surements were made as t he phase angle was varied and the Pitot tube kept at a fixed position ac ~oss the volute. Fig . 21,22 , 23 . and 24 (pag es 37,38,39, a nd 40) show that there vms practica ll y no velocity ,,a r1et1on at noru.ta l pump discharg es . The slight wa vine-ss in t.hes.e curves mi gh t b-e due to va rlat1ons in impeller dimensions and a slight i '"'- eller motion in the axial direction . '1111s lack of a veloclty va. :ria tion wa s t'l. lso found 1.n o. single suetion pump test, a nd will be discuss ed l s. ter. 'l'he P itot tube was a s h ort dis t ance fr om t h e i mpeller, and .it 1s poestbl0 thfi t a large vel oci. t y v~u•ia tion does exist in a very short r adial r e,:;ion close to the impe ller peri phery. The Pitot was nlaced e.s c l os& to the impeller as seemed a dvisable . In one cas e t he re wa s 1/an ( one-half Pi tot diameter} clearance he tvieen t h e impe 1 ler a nd the P 1 tot tube • Sugge stions have been rru:td e to c onsider a shorter time of va lve opening . I f' a l a rg~ velocity va.r:l.a.t ion did ex i st in a s horter time it would be o f minor importance, at least for t he present, as compa re d to s ome of the other ttn9'nswered problems of :internal pump fl ow . I l ..J I. i i r I I I ~ ,v: ~ 1'"-~ ~ ' .. + r-1 ... ~ l I l r1 I . -I . ~--~, ~q' . .t:,r-,-:. ,. J , .... 1 • I '7.' -39 :... ♦ - f ~ ~ l .' I I 1 I j ~j I • • • • • y. • • .5 , l ~- 1/4 • ' '1 l/T/ON ~ ;l;?),s, OCI W.£ N \ V~N't:s\ I . ./' t ►_.,- • ~ 6~~r1~?-•-/;M~~nr• "I~~h r;~;n,_1,.~ L . \ ro _·~ro 'J: 0£ , 1 , ' '·~-f ' _,,,...~, · - ~ f • d.... ·--iJ JmdN : J;r1cks ~N --4- - • - -1- • 2900 R. ~ M. NoR.MlrL. q J. \f ,._ '. . ~ '>- Po1.1tilE.•.5vcr1;N 'Rl/'M +· ............. ... - __ - - • - ..:. - \ '.... I 4.65 Co. rr. 17£~ S£c. 1 FIG.23 .J I - - '806l lltlli,;(oo::, . ' . : /,.. ' ~\ . ,:·- 7' ' }/ \ V - • --~ l / .... ,i.;_ IL t l ~ .l r ' ',:.., ; i:T ,._ t~ ----.- --· .A.:f. A .' .~,r- I •/ ~ _,•1 ,......, V .. ' 1-1 - ~f · ►• .~ I -~~_-1/,-~f~tl, . , - ~x / i ~;:' I -z 2 j -..... '\-- • •~ f j ..___ I ,~ C . ~I ·..--ztr . I-,..__ i 0 41 - FFECT OP SHROUDS O Pig. 25 nd 1n d tr P1tot tub t v ne bet de One not1 ges 42 ; 1g. 26( ob t· nd 4~ • tr verses aero the se ngle . cons r bl VELOCITY DL TRIBU~IO nt ture 1a t e w re first built clea nee b tween the runner nd case. 1nd1c t d 1n m le cl roved by allo shroud and th eaa --~ ~I \ rot'iles olut, each bro • P D re la volute 18• 27, w1th as 11 tr, pump efficiencies nee betw n the Mmner • shown in ' t e tin o tea eat elocity ou~ id or the pos1t1 ar, 1 • 28 . 1tot tube I \ I /[\. ur m nts of r cle ranee n x 1 nation or the 1m oved e~r1o1ene1e . llowa use to otherwise would b d1 si C ing. e de of so ted 1t t or th ener d between th which shroud nd Page 42 ~- 1· ~ .~; -~-!;j ~ . _,___, I• ~ '.' I I I I ,. l; ~-+--+.;......--' ~t:~ -~L'1. .:.·,•· .r~; -. • ~> µ 4· ...:-r;..: ~ ~: =:i-,.,.=........::lj,. '';-;,_. I! ' I ,r- . · ' ' ' ' _.·._ l_. j . 1 '1- . I. 01-- ., •. ,,f1):: : 1;:. ----~r+-:--·: I, , '' . : ; :· . , ;-------- ----:-. \ j J. . I - . ' 'I l! ..... ,, I - ,..1 .. • I:· '. P1~4j-, ' ']-., 1 ~ · ':!' l") ' :1' 4-- - - --...-+4.-"-,.;...,+l-..+C..,.=.,c..;-+-....J • ! •-+-..__.-'-r ·1 1 --'I~ ,J1-- T - •t '. _.:._,'_-__:-_ .,.- j ' . . . ,....,_ Ll" ' .. i • . re ·-1---~ " ",, "' .r :z . ii • I ! ~ j,.;;· ;'-'~Jf : ••• .: • iik:,: ~ 1'· .· 1r.0.•·"1 . • . • ;.__1.:. ((6-• 26 - lNs r,qiJr,.qf.1£011s-· Ve-L oc1TY 2000 R.?. M. No. /2 NOR/'1/il. 4. ~s: Cv, rT r'ER SEC. Pp.5;-r10N 9 M6. ZiJ Page 4.3 lnPE1.1.Ek VEt.cc1rY :: 116-B Fr. PER .$£:G._ IR ,.q VER sis ~c,eoss- Vo Lure - BYRON "vilcK.5()N 1Jou8LE- 5ilcr10N ?vMP 11 0 ° ?//ft.SE /9Nt:;LE ¾; .r,eon hrar C£NTE..fi ;..o /MP£Ll.JER Pos1r10N NoJ2 .LowQ ?os1r10N No. ~ No.ieM~i.. q low 9 0.18 Cv. rr. P~~ :J);c. 4,65" Cv.rr: ?E,.e .SEc. · 0,18 Cv.rr. ?ER. .5£c. No.9 Po51r1o;v · , '. · 1 I ·: ·- - ___ 70 •• ~ _ ... . --- , 60 1 •l - ' 1 I 50 --i-- I· L L- 1 .i ----.--- I ----~-I I -I- . ___j_ - · --.- -·-- 'I I • .L --r - - ;_, . ,I I I - -i-- -+ L I I I 1 . .. t I - . .! - . .!. __ _ '· 40 .' I I .J - I i-- - T I I ·l - - l - • I I --tAOI~ C~MPt>N£H r J_ i o~ .-- 1. I - i I __j lisso4vrt= VE4ocn, y -T · I l .. - t ... - I I I I ' : I . I , --~---- ·+- -- 'I I _J -- _J ___ - -, J. lf.?PELL£SZ ' I , l I - 117 - --- t· . - - i _____ . J ' ---1-----· VfNt,J.•L /185tJJ. J rF . j - JS ~ Vl 10 l,\i ~ 4.J ~ h. s~ C)::> ..-1:,----t9-~.\..:· Vet..QC1TY 1'1At'ES WITH ' /M,PJ:,1..1..E~ ,tRNd.E.N.T .f. .j.. • • !.. I I I __ -I I I I '_. - -- l - 2t -5 ~ l:_ _ . _ _ _ _ . _ _ _- - ' - ~ ~ 44 Referr·iug to the radial velocity prof'iles at low pump discharges, in each tratrerse ther-e are two outstanding high velocity pea.ks . The most reasonable explanation of these peaks lies in a eonsidera tion of' the centrifuge action of the shroud . Prof. von Karman. has suggested a calculation to help explain this matter . In the following ealeulat1on no elni.m i .. made to express ~xs.etly the extremely complicated or.>ndit:tons in a pump , but the eomputation serves to give the order of magnitude ors vera l 1 factors . Prof' . von Knr•n. has treated the problem er the frictiona 1 res1.stnnee of a rot..'-l ting disc for the case of tm"bulent flow. He considered a smooth flat di.s c \rif@tted on one side. 1.,ie various momentum changes were taken into account, and the veloei ty distribution in the boundary layeu-- was taken 1n a.oeordanc.e with the seventh-root lavr . The following ex ressions were der1ved 1:n the tree. tmen t: whe:N~ c0 = maximum radial. veloei ty in the boundary layer R :: radius of disc w = angular v-eloai ty of the dise S = thickness of the boundary layer v :: kinema tie viseosi ty of the :fl,11.d. 'rbe above is for th& t of fluid. on one s:lcle of the dieo . Fot" a disc wetted on both .aid. s 5.t would be i:as sho-wo di,.gr uma tically in r,"i g . 29(paga 455) . 21.),.; ~, Uber Lamina.re uud ''.rurbulente Reibtmgtt 45 FiG-. 2B Applying the above two relations t o the particular ease of this double suction pump test, and ta.king for R the radius to the periphery of the impeller , there results; Cc::: 18. 9 Fr. PE,e 5 £c. S ::: o.;.511 It is interesting to note th.at som of the me1u1ured r adial veloei ty peaks a.re elo-e e to thi,s computed value or C0 while the measu·Nid radial veloci.ties over the eenter of the impel er 11e betwe,e n 5 . 0 and 7.5 f.Get per sec. 1iote aJ_so that most or the peak veloei ties occur at a point within the eompu.ted bouncltn"'y layerthiekness. These facts g .1 v0 a go,)d inciieation that while the flow over the impeller eenter 1s being h~ld back each shroud a.ets as a centrifuge to disc harge a sheet o-r wiiter into the volut .. The question might be raised as to why there is a laok of a 11 s}:l.adown 1n the veloe:l ty profiles , since, referring to 46 Fig. 29(page 45' J dil•ectly over the shroud thi.okness there should be no re.dial flow. For this pu,mp ea.eh shroud was about 3/16" thick • . lso t.Qke into aee·ount the hi gh value of c0 and. th® f'aot. that the pm11p is being throttl.ed . In view of these fa.c tors it is quite possible that in a. very short radial distance- the flov1 from ei thtH' side of th$ shr-0ud could dtverge ~ and. t ha. t in this short distance these divergences could combine to gi ve an, a pJ reciable positive veloe:i. ty ovEn-~ the shroud thieknesn . Ther-e is an.other question ns to th0 aouree of the we. ter which the out·e r feee of the s h roud may discharge into the volute. · nother pump test t.:-tt low e ~:ipaoity showed radial i.nflov1 ( Plow towards the ax1s of rotation) completely across the vol ut-e, in a short region at the upstr~am side of the t ongue . From this e.xperi.m.ental evidene& 1 t seems quite llk®l.y that at low pump ca pacities there is water flVails.ble for the outer faoe of the ,s hroud to discha.rge into the v olute . All these eonsidEu:>a ti ens serve to offer the most ret:1.sonable explanation of t he unusua l radial v0loeity prof i les found at low pump dischnrgee . Fig . BO{page 147) show t he various veloc1 ty vec tors at Posttion No.' ' 2 which is t h e nea1•est Pitot str:1 tion to the impeller . - --- - ~ ~ \'I\ \ TO J/RN£ ·FtG•. 30 . ,,._-TRNGENT Vt9NE-- 'I"" "'r ·-. <.. "" ~ ~C" ~ 't""-» -"' "J,,. 0 3° .4.S <> ·o 0 -,, - ~. ,. <'(' ·~ ~ ,, ...-.,.._;::,.: A .-(-.. .-<S ~"f" C' ~ ~ ,s-' ~,f) ·,o ~ :><':o ~o-s . C' 67-.I . ~b" RtGHT 72.0 CENTER 7 " · 5' ~~ " LE,r 2000 R .P. M. Q =: 4 ~t;,S Cv. Fr. PER 5£c, ?UMP No£MRL 13-J MER5vREMENT.s ·OVER. . . IMPELLER. rR"M Fos. No . 2 VEcro,z~ ,q7 ~· 4 48 With the Pitot tube at on$ position in t he eenter of' the v olute , the pump ,c a pa city was varied. Th0 results a re shov.rn in Fig . 31 (page 4~J . One important i tern of cons iderable pract i cal interest is shown by the Pi. tot sta tie pressures at the two sta tions ne a rly l l, clegrees apart. l~ t l ow flows t h.er~ is an appr eeiabl& d.iff-erence :in static p:r•a.s sure. sh:<)Wi ng ftVidf.me11t ,.,,i.' e.n unbalanced force on the impeller .• At low flows t h e pump is a good fatigue t esting ma chine , arid·. t hi s unbaltanrH~d foree may be a s e:r•ious matter . It me.y be enougl1 to d eflec t th~ impeller t o eause and ln a~vere c a ses to break the pump shaft . t~ote t lw. t fat high purnp flows the unoolanced f o:r~ee change s di rection . I f it is a ssum@d trui t a u f're-e v or t e,i:1' exists i n the v ol te , th@ a ngular momen.ttun wi1J be. constan t Hnd the pr oduct HV 1s c onstan t, w,i1.0re H is t 1:e r adius t~o s ome point in t he v ol .r te , a.nc V s the tnng~n ·ial veiooity a.t t hcd: po1nt . Nith t h is double sucti.on pump t he i:nvestiga.ti on we. s 11m1 ted because it v,as not poss ible t o provi de Pi tot stati.ons 0.rou:nd. the entire volute .. However , in a single suct i on pump i. t was r-r:, " ,~-~ bl fJ to provide sta ti ns around the ~ntire volute, a nd so the fol l owtng section g ives the resul to of ~- m<'lre complete s tudy. I I -i- '1 ,,· I L.I ...-.- ...... I -.; • :.i- ', .....!.f ... l •; .. r- b+-; ....,_,[. I ..........., __-i!,..-~_._ • • . : .. -·,, . ... , ' ·Il • :' .I:.. I . . . "I'!:.. t- . ' •• - ~~--~-I: ' 'I· ·r - I• J ~ .. • .• : , : • ~ t ~J!P '.: i 1 1 : H, t1}--t·i IL:· , -~: - ~ ' .- ' --JL j . --, ' ! '' I """1 ! + ' .._ 1~·j ~t . . . ~r ,.:...:_:. ! ~._;-~I•,, ! ~;: j•~-t-~ I- ' 'l~zj'-', I u,..'-'--2.,'1'+:-0-.L.;--'-!.;..._;,..:._;.;.--+:--+t'JK.c--r - i_ i . :..r• I ; I!'"' ''' i1 , : ·1·;,_1_.r··.1,: • - ~ + - ~ - - a -- '•.· •.a-rf.ti;:' I . - ' ;.rt c. • " l " 1 '' i - ~ i - - - -wt-+--:__ r_-;-:+.•.-::--..:_~: : 1 • - -+ ,.. Lt...-''-t'.;..J._,ct'-,_'•.,+--'-'-+-J:-it---m,.,.;.!-4-'-f~r+-+"-+:,c'-,-'-4+;-;+;-==.:+;+i.;R- qr1 ·.-~ :~~i:·Lli 1 > ,.}. :1~t 'J•j' .. ~J t) .:.:;,:.•I . ~ ,-.-,~-,'.-_-j.,_. . 1< ·; .l . t'i:1--1 I.! ~· .:-: l'' _:i:: T ~-:: !1, - ~ - - - ~•+--~-+ '.7-C:-t-..i-:'7''1- ~• ' ,'(:-;;,,.r ';-! _Jl- •--:· r., ~~ ~-r~ .._~ : \'.I. n"l· 1 ,· t!1 i' • 1 i l~ ~ ½ -~ :~. ~ I ....:..=i-r-::.;..iJfi+Jl!I{' ·-'+--+..+l+'-·h-~---n-1--,-'-'-'··++-~-+.-<c...;. 1 1· - ·t_. • - 'r' '°"-r-:'1 .:1·,, 1·~1 f l ~1, 1 1 • -• . '...:17•:..1 J ... ·,· • - LJ 1; • j ! I "" - ... • 1 0 '' :I _t :~~ ~j f~ l.)~1:t)t :_, { fW-..J ': ;--,--.-4.,..;~t:-_::- i., ._t-l • 1: '1 rr~ i ~ I ~;: /T""-:,--t+r1- l ' --l,.. ililt :; ~ ·t•-,_,-,.-'r-:-+-:-1c---1~t!i~T"'t'--'ll:r-P...,.....,'---~"'1-rl 51 l'NSTAN'I'A NEOUS VELOCITY MJiA3U.REtlJ~NTS ON' WOH'l'IU.NGTON 7" SINGLl~ SUCTION CENT RIFUG:;'1,L PUtiP PU-MP Rfo..'J:l.MG Ali!; DIMENSIOliS Serial No . 887789 S ize Sing le Suction Type Capa ci t y 2400 G. P . M. Hea d 360 Feet Speed '2900 R oP • .M . Specific Speed 1720 Im l ler Outside Di a.Ji ete1"' Impeller I nside W1.dth Impeller Outside Wi dth Number of Vanes 12r1 1 7 /32" • l 15/6411 1 17 / 32" 7 Al l purnp ru....'ls were made a t 2500 R . P . M. 'l~e maxi mum effte iene y ( 8 8 . 6%) at 2500 R . P . 111 .. was the s ame as a t the rated speed . All tests were mad$ at plus 40 fe et inlet head . :t•'ig . 33{page 52) a.hows the s pa cing of the : itot tube stations in the volute . Ex t ensi ve tests we-re made a.t three different pump d 5.scharges - 11 normal" , tt 1mv11 , and "hi ghn . nNorm,1 l r1 pump di scha r g e is tba t at the potnt of ma ximum pump eff'icieney . "Low11 refers to a di scha r g e less than ° norma1n , and ''highf1 ref('Jrs to a discharge g r-ea. ter than '1 norma f 1 • Page 52 OF D1MEN.$/ONS l?ror Pos1T10N HR'' "8" No .. R,t1D/IIL DEGliEES 8 C // 0 11 b. 70 11 6.68 b. '1B" G 157.b 224.~ H 6. '18" I ~-72" b,11" 6. 71 6. 71" 2b9.! 2 '!J 5.4 314.5 334./ o.4o" o. 4&" 354.8 0.46 11 I( Wo-.en11N6TON .Sc,'11..E: StN61.E 4 .51z£ HoLE.5 .5vG TION PvMP 0.43" "· 68" lo• 6~" 11 CLOCKWISE Ptror o. 43 II 0.4l '' o.43" 0-44'' 0.43 ,, o.47N MER~llllED oF 49.8 "7- / l,.67" ~-66 II Loc,qr10N 0.45 11 o. 41" J P,ror 25.S 90.2 L /1NGi.£ CENTE,€ 135.4 r ~ P1TOT 11 D E D D1sr,q1vc£ To IMPELLER D1sTRNc£ ,q Loc,qTIOIVS 7usE LOCRTION.S 53 .!!iSTANTANEOUS VELOCITY DlS'fRLBtrfI OM ) BETW;EH VAWI3:3 Fig., 34 to 39 inclusive ( pages 5:.42 to 5"97 inclusive) show the results of mea-s urements a s the Pito t tube ~m.s kept at a :fixed position a c.t>oss t.he volute and the pb:1.se e.ng J.e varied . Note carefully the coordinate scales uaed . Fig .. 34 and 35 sbow that there was practically no ve locity variation nt normal Plli~P discharge o Thia was the same as found on the double sue tion pump ( pag e 06). 'ft' ig .. 36 and 37 shows a slight c hange 1.n vs looi ty with phase angle at low e a pa.c ity . '1'he flow is not exa ctl .r periodic . At low pu.rnp ca.po.eity the veloo1 ty hetid fluctuo tions were much greater than at normal ca pa city { the head .t "luetua tions v.rey,e not gr•ea t e nough t o seriously a ffect the accuracy of t he ) mea surements) . tfhe qua litative experiments of F ischer and Thoma 1 have shown that at; very low pump eapa.citiE~S " the flow eonditione were cha ra. c terized b:r two different crt teria: 1) The outwa rd. flow ).s no lon er stable a nd ve.rying cond.itio:ns of rev~rse t·1ow appea:t•ed . 2) J, t any given tioe different flow eondi tiona we:r~e to be found in the different water passagElHl' . Reverse flow here refers to the dead-water zone c omposed of whirls and edd ies , the zone be ing on the low pl"essure side of the van0 . Thus the present measurements agree to some extent \r.ittl~ the findings of' F i sche:t" and '.1horM. . However, the tn~esent measurements show only a slight veloei ty variation at low pump capaci t~r , and any conipa ;r•ison s hould take i n to a cc ount t h e :rema rks !!I.a.de in the Introduction of this paper .. Fig. 38 and :$9 show a. sl .i ght cr,..ange in velocity wi t h phase angle at high pump diseharge . -s ;A . S . M. E. Tr ansa ctiono,1932 " "' p ~ ~ 0 0 z z 0 ·9os1 )4flfJA:doo ""' ...... "'r C ... "'~ l) 0 0 w " ,., ~ ...... C ."',., r ,,,., Ill i l> n 0 2 :z 0 57 - \ - )-:,,, • I,...t, I ."... C ...... ,.. ,.., i., ~ . ,/ "':0 0 0 z z ? ~1·/1-.J. 1::t-}. I -,"l .. ·- ;:W.: -~-.:...,:.... ~.,,. =-1--- . . I-· i ·*ift~~·2}~c +_.;+~ •r' r·• ~ - ➔ \. ..t ' , ~ _I_~ w ~ ~ tt ~- - l .t... j- . -·-, ff -~_,I \ r· .~ ex.'.: -~~ '.LC,_ / ,)t,t-0) 'sl,r-¥:7. • ~ r·: . . r" 1.,,1 /.~)<r,f, 1...t-r~ • -_ '-./'Y i-~; - - -- ;1 t fH- .. CL t: r.nL!..._•t ........~ ' - ' - ' , _ / , .F~ . ..... r•..._..itJ ~ ,.. - ...ii..;..w.1.'-"-'-LA~ ~ __....._......__ ..... - . - "'h' 58 "" L ~ ~ "r ,., ~ ., " 1/1 ► < . ~ 0 z 0 .J-~. N ~l'iii·I .,_..\:-rt· -" - ~- * :.., " . -1-,~ ·;/ i'71 1f~1J I -1'. ::.J • -• "'--..i I - "' , ,-,-1 i I ~ I \·'J, •. I , ' .__7;-, _7 .. ;--""::- .~' . · / ·- ,,. ...... ¥ }:L, • 1-!.-..-.......,._..... -• .. r .. ;- l-- .......... ' ' --t'I I 2 0 60 VELOC.I'r"! TRAVERS ~s ACROSS VOLUTE A. ) MORMAH PVMP , qAP~ CI ! ! Fig. 40 and. Fig. 41 (pages 66 and 65.' ) show the profiles obtAinecl fl"om Pitot tube traverses across ··he volute, eaeh traverse being made at a constant phase angle . Recalling th.ft notation diseuased on page 31, the 1"1ght side of tl1e ,-1npell&r center ie the inlet side of the pump . Beee.use or a prejeetion on the pump at t?¼e time or mea surement Position I is not a complete traverse . In the f'e.mila~ diseu.s s1on of double suet ion pump vs . single suction pump 1t is somet1n1ee claimed tm t the double suo·t 1on pump gives a better or more symmet:rienl velo-e:l t:, d1st~:r1'but1on. A. eompL1"1eon ( ~f Fig . 40 and Fig. 41 w1 th Fig . 25 and F1r3 • 26( pages 42 and 43) shows that the abeolute velocity profiles of the double suotion pump are slightly mere symmetrical tban those or the tingle suetion pump . Fo,r a majority or the t1-averses 1n the s1n€1;le suction pump the maximum absolute veloei ty is to the right ot the impell.(!tr eenteP, while the double sue tion pump profiles show the ma,dmum absolute veloeiti.eeJ at the impeller oente.1-- . Th&se Pitet mef.:i.sureHnGnts show one gtmertil :result and. that is tha.t the flow oond.itions a re not uniform a.1~ound the volute . Fig . 40 and Fig . 41 show that the pretiles d1.tfer in c:fhara cter and magnitude . MetR.sure:m.ents at other pump ceapB-ci.ties yield another general reeul t a nd. tlia t is that the fl.OW' conditions a t norni'al discharge are more urtiform tJ1an at low and high eapaeities . This latter result ie quite reasonable when aeeount 61 1s take,n of' the- faet that at normal eapaeit-y the pump bas 1"oaehed its m.aximtim @ff1c1 e.n-0y, imd therefore the flO\il eondi ti.ens should be t he n1oe:t .favors.bl®. This lac· or unif'o1"'r.n1ty of flow concUtions .ts indioated in :ft,i.g . 4S(pa.g• 68 ) , a plot of aver~g& radial v eloeit-v vs . angle around the volute. i'or eaeh Pitot station i n the volut.e ·t he a verag e radial v~loc-1 ty was found f~om a complete; traverse a cross the volute., lnti!tgvta tit,n of this mll"V$ and a e onsid@ra t:1.on of the area gives a net quanti. ty of :flow whieh should agree wi..th the fl ow register6d by the venturi. me t er • Fig. 42 shows t h1ll. t the a greewr,nt 1f'J not exe..et, but t he agre0ment is quite close tak i ng into aooount the eonsidera'ble sepa:ra ti.on of some of the Pitot etat,.ona. 'L'his ag2~eem$nt · ePves e8 a cheek upon stations eould not llave been provided because of' proJeeting stude. and obstruet:ions on the pump . v rn.OOITY TRAV~";RSE!S t' CHO$$ VOLUTll: B) !.,OW PUll.{P CAPA. CI1'fr • • ----• , Fig . 43 and Fig . 44(pages 6'9 and uo) s how the profiles obtained ~rom .?itot tube tra vera<~s a o:ross the volute at low pump disoharge . The profiles differ V01"'Y nm.ch in both eh.Qro.otei" and magn1tu.de _, and show that the flov-1 conditions at 1oi.v ei,paei1::y are very much leas uniform tl'~n at normal oll<rpaoi ty . There is a more or less progressive change in the profiles fi•on:1 &ta t1on to station . Note particularly the 0E1ses ot inflow, that is , flow towards the axis or rota ti.on . At Position L th.ere is 62 in.f low eompl0t.~ly Qeross the volute . With the fl ow thr-ottled., th-ere is probtfbly a dead water zone in t l.10 di.1'1\1.ser, and. bhua th0 impeller outflow( in other pa.fits of t h@ volute) is fotfced be..e:k in tOYJards the imp@lle-r at tbe tonguo . Fig .' 45(page ?i ) shows the average iroadial v·e loei ty d.1at:~1but1on around the volute . B@t-we*n I'osi tions 'L and A th.er$ is a very appreciable , abrupt ehang{l) 1n the a verage radial veloo1 ty, and naturally a. que~tion $Xia ts a s to woo t eurve to draw between Positions L and A + 1l'he Otil$ given seems tb0 most 1. . ea.sonable and oonserva tiv0 . On the basis of this <.nu•ve the qu&ntJty of flow indieated by the P1tot agrE>es very closely v11 th th.0 flow r~gist0ri,d by the venturi meter . 'This elose a.greemen~ in these ~ra-atie flow conditions speaks well for this technique ot meaen.n:-lement . fif}f$rrlng to th~ :riu.U al velocity profiles 1n .t?ig . 43 and. Pig . 4 4, in many of the t rB.vera~s Il JN~ round two outstanding high velooi t:f pe-aks , as waa o\,s0.r ved in th~ doubltl suction pump t f<lts (pagfl 44, ) . Applyi n g th(!) two reltations discuss~d on page 4.4· to the pa:rtiouls.r caae o f this ain.gl~ suction pump tttst there r@sul t~ & Ct:,:: 22. / ~ = o.;411 FEET FEIZ SEC. where C0 = max1ml'JJ'll t>f'Ad1a1 v01001 ty in the boundary l&yer $:: tbicknt'HlS of the 'bounda ry l a y@r Herei, as in th.Et double suction pump t est, one no t es toot sorae or th~ meaeu:v.ed r ·rH-'i1a1 veloei ty pea.ks { in th$ eases of double peak p:rofile-m) are close to this computed V8. lue o f c0 • Mote a l.so , 63 as ws..u ob s.e.t•ved in the double imotHm pump teff t , t ha t many of' the peak veloc i ties oecu.r at a point wi t hin the computed 'boundar y la y~r t hi ok n~so . Undoubt®dly other factors besid&s the &hroud are aff:eeting th& imp eller fl ow. but the pr,u3Q!'lt point :l,,s that the mos·t roa sonable e xp l a na tion of t he ht gh velocity pea.ks sta tes tbs. t t hese pe ... ks are due to t..'1e centr5. f'u.g0 ac tion ot the ehPoud. The inflow at su ch sta tions as Positi.on L eould ea sily fu.-rnitilh water for the outer f'aee of each shroud to di ~J charge 1nto the volute. Vali)CITY 'l'AA VJ{fiSlfrS /; CROSS VOLUTE <U HlOfl .. ~ UMP Cl lill.!I i 11g. 46 and Fig. 47 ( pages '70 a.nd 7i , show th.~ profiles obta ined from Pi tot tube t r-a. v ~nrses at high pump oapaei ty . The traverses are not o.o mplete 1 but the measurements a1•0 useful to some extent in a comparison with the reaults of tests at normal a.nd low pump oapnci ties . '£here is a d~fin.1 te prog <tssive change in t h e abso l ute velocity pr of.ilea fro1'.t1 r osi t'lon A t o Po$i tion F . Some of t he ra d ial veloei ty profi l e s a.re smoothe1~ ~ind more s yrttr~etri ea l than t hoso at normal ca pac ity., while oth ers ~R~e as distorted s s thoa (l) at low e paet ty . F1g . 48(page '7~> s h ow th£1t the r a dial velocity d1str1but:ion around the volute 10 much leas uniform than toot at normal pump dischar ge . 64 tfNSAtA?WEQ ;RA!)lAL FORCE§ .~AC.TING o, IMPE.L~?t.D F1g. 49(page 'W5, :- sbo'tf1s the ste.t1e pre-sauro d1$tx•ibut1on a r ound the volute aa given by the, 1"itot tube . The stat1e pretu1u.~e plotted is that developed by the pump , and thus does not include the inlet pr11uis;ure . 'l?he dotted horieontal lines indieate the mean st~tie pveasur@ w.lue for each pump capacity. 'rhe static pressure ehows the S•ame general trend as • s obse·r ved with other oht.trm.eteris ties of the pUK-np flow . Fig . 49 shows tbat at normal cEa~e1ty the static pressure is much more untfomn a round t.h~ vol11te than that a. t !?,igh and lQW cii1pa.cit1es . Ft1J'.'t?le:rmor$, t.c¾e statie pre·ssure1 is not exactly uniform e. t normal ee.plll.01 ty . Lacltt of' unifol"mi ty ind.ice. tes an unbalanced et~. t~ie presstu•e force • Fig . 50(page 7&; shows both the unbal~no0d static pressure and the momentum fore-es acting on the impeller . ln th& abs~ne or othel" d$f1n1 te infornw. tion the wi(lth or the hnp.ell~n" was taken as the area over whi.e h the sta tie press·ure a eta . Beoauso or a lack of un1for!n veloo1 t-y distribution around. th• volute there !>a a momentum tor•ee aet1ng on tho impell.@l:t9 . Fig. 50 shows that the momentum force is small in comparison with the st.ft.tie p.ressUFe force . lt 1tt interesting to note two features about the eta. tic pr~ssure f'oree , the momentum foroe , and the reeultant f.O1>-ce- l) each fore0 is larger tor low and high discharge than at riot~l disehf1t>ge • 2) each force changes direction as the pump disohe.1"ge is inCl"e{¼$0d from low to high. 65 POW 1 'H BALA1iiC 'F£ AR{>UND VOLUTE . -:'1'\ Fig . 5l(page ~ &hows a power oo.lsi.nce ar•ound the •olutt'i for lov, and high pump d.1 seharges . Th.Eil !J i tot horse- power ns oomput@d fr()m Pi tot tube m&.asurf,'m@nts of total h0ad s.nd ra dia l veloei ty ., The total head 1.s that total head develop ed by the ;pump and the·re:f-ore does not include the inlet head . 'l'he area und&r ea eh curve in Fig . 51 g1vea the total ho:tnle-power at th~ ima.i irw.ry oylindr:to a. l aurfirne whi.ch pass ea th:i')Ough th& Pi.tot st.at1ons and whieh extends completely aero&s th0 volute . For low eapao1ty• :the inflow(tow~rds the axis o? rotation) accounts for the nega.tiVAI.'l powev V.a\ lues . Th0 ·a bs.ft input h.orse- pow@r 1& the p "1Wel" input at the. pump 1haft . 'l·lie diffe1N1mo8 botw$en t..llie al:iaft 1nput horse..-pow·e!" and the Pi tot horse•p<>w&r is l abelled 11 impelle.r loss 0 for the sake of eonvenio:nee . Actually this so- labelled .. impeller lossn ineludes raore than the losa 1n the impeller proper . The power d istr:t.butim1 is me:Pe uniform at normal eapa.ej,ty t han e.t low eapaoii;y, and further, the power <list:t~ibution is not exactly u11i fo1--m a. t normal eapa e1 ty. --:.l-. rRtrrE I ~ •• 6/8 +-t=ier. 42 -+ t : I rj-f ➔ ..i'.. • i l --i j I l l ' r- I _,_ -r--.4-+ ! · . ---,1. l _! , ~ - - r ____,__..+..........---1i---;_-'-----1--~--l--+---+---+--+------- I ......... I .:.... •.... •'· !?VER. ~11.P11r1. Low Q VEL0~1ry 1-+t 0t. J: I I· .. -+ -- • ~5._ __ I • , •• t ! l ~·: ·- ...,L- .... .: ... _; l •- ! H£ . 1'avi. _4_1>£1,i.Yt L VERA,~£ :O RA V.ERS£ · OLUT£. I ' ~L.£~[ , TflE : "- , ' /?VE~. fi:l)Jf?~ 1/JGfl ~ VELt>CITY :r ~J ~:~-t~~-': f :• '•-::( tr·:t>+:.--'_-J~• 1 .:.L i::-:··1 ··-·-t . :L .. .r I -· -1 1 •···i · -.. - ti~):~ t~ t· ~t I . ' -t: · ! ·· --➔ · - - 1• J +-·, :····~ ·ii ··:·~ -:-r •• . ('\ - ~ t~ =t: . . r·· ---~:r-r-: . .:.J . ....L . l ~-fJ_:Jt f -~ _.~ . •. • •1J],'; /· I . . ~ l -. :~·:7:~;:r:-·> : !i --- ---1 ·,.... ···•·I·•·· ···-·1•• • : :, :µ1::-:_1: :~·· -·,-12. 1, - --:: 1::. ,· r' -l ,...J. ~ ,, I i t • • -· - \:::: ,, ' :' •l !I' - r -- , ... . , . . . _ • ' J 1) I I I .'. ,... . i I - · - , I : ;· · :~ •• . •• ' I· :-•: · ~ ).j.; \~~,r:_:_ :~_:.1~;.:L l(H +:i :'.7:j;-r·~ ..,L,.!tt~"tlL..:+U.;Jt+Jlw~At++.::~L.m1ff½+~tttiBW,+s-~~P~ :m-iilv.-t;-;tt i•.·---1 :,r-: :; ... r i-i~:'; ; , .! . 1 !.~!-: . . • 1:J; 1·! ; ) E0iff frH!i ;-:',; '.2L~~~ ~1~ ~-k.;;_l,----:t~~+~~+h,:-d~ H-~+~r + r 7ft~f',-t:~r--:-:-t:-~~::-t -i:-:: : !. .• • - -'- · . .. . ......,--+T: / -~ 1 - -,.. . '.• :~ •; t1~/l . l •-~- ~-,: :+·::+:: .. .. . ·: Ll -:\~(; ;·; /-\\::'./ii: ,. .' . . 1 J y Nor£: ''.5 r~nc PRE.ssu£E Fo,ec£ l<ErERs To 5rr1nc P,e.£s.5vlil£ /?cr1NG OF IMPELt.£R 11 ON y STATIC f'RE$5, RE5Ui.. rANT r°ORC£:: '15 La.s. 16 LB5. RE~u ... r,qNT roRc£::: II I La.s. PR£55 . roRC£::: MOMENTUM roRCE = .32S LBS. (I;; ) y Sr.qnc rc;fC£-:: 40S L as UNB.,qLRNCED /9£Ei'? W10TH y THE 11 MOMENTUM roMcE= 165" LBS. -x ---x roRCE ~ /78 LB.s. ----RE5UI.. TR/Yr Low Cr1P1tc1rY o. 996 5£c. Fr- F;&. 50 • NoR.M~L S.29 UNBltL/tNCED CRP"1C!TY 5EC. rr. r'ORCE.S woRTHING-TON liCTING- 51N&L£ '? ~/1,.., /ilGH 0 0 IV1 7. 5 4 ON Sue r 10N C~PRCITY .5£c. Fr. IMPELLER { R/lD!rtL r°ORCES) PuMP roRC£=- 222 LBS, ?owe~ lJf?'-f?NCE f1R<.1vNP Ve1.L vr£ ' :- PowEf- _ ,.i,.qL,q;vcd f/,e ouND . VoLVTEI I Wo,e THINt .:I. !1 ·• ·, --- ~ ... _ 1_ _ •___ - - - · - - -- ~ -- ' __.._·_' i rtG.-5/_·- I -t· ·· ... .. ~ . a/\/ S1NGL . ..~i · ,· L S 'fC T~ 0N i-• • i .. . ..... !.---- -, ! f.'v/2P c l 250 Q R.F. M. · , • 1 r 1 1· _!:.f:aaL_~.E'.tJ.Wll ,, RErE~ L .z::a_z::tfL - POWE& ..J.BL.:.ALX_. _ __ _ _ ___ _~ -- - ---....---· -- - - - 'JM/lG/NrJtflY j 1 . ' L 1 ... 1 l I ··,•·-- .• YL INJJ/e!C.it.. .5.u,e/ffiC£ i. ff/?S5:ING. i. T#fOU.(;H .Tfl£.. f'.LT.0.L .OB.£. 3 T.iTION...L /~ . .T.HE !. VaL.VT£. -- jTHI? , .5 (IIZF./fC£ . £ X TE!Yp5 , COMPL£T4L Y /ICR- 05$ Tf/E rot.VT£~ -· -. -i · ... ; • ·--- -- _·_ i i --·- t ·- . . i -. . . . · ... . .. . .. . .. I - · ·- .. - · I 1~ I· - - J__ •. . -- ! . --+. .. -i• I - -~-.,__---+- ~ -- - - ~:_______,__4--i- ~--+--- - - -- - -·~·::_-_ ~--+----+----- - ·• -; _ -- _·.._·• _.._- _ ¥ ' - •·· - ~ -..+-:. •-..-_,_-___-, ,- J ·- .. 1- •. , ! I, -l I - + ·•· -:-- .... ·/-·. -I i .. l '£ ::i?°-WE:e . B Y : PuMP i flo_g,~E- ?'ow£,e _ i __L . .- 5HBFT P.1r.aT I IVPI/T H.'P- f!.P ' i • . .5,H.f'. f'.11.i'. .5.HllFT INPLJT Jf0.~r E - f'qWE£ .. NORM/IL C:.RP.llC!TY LOW C RPI/Ctr'f i ri ! 7, 'I 171'-'1 /89.I 58.5 '17.8 37. '1 2p.6 ... j. I •I - i I : . ___. ,.....7 ·- .··-: I I I j- ·z~ w CR;J?c~rY ~ O, 9 % • j • ! ; .! w. Hi P. - ---~ ! I ... £1'rtcl-plcr i .-- ----7-· '(o,ei:1/ll.. ' C11fn c1rY =S.2.'1 i • ovE:eAL · l.i Cv. NOR 1'1111.., •••ciif1,c1rY • ~;:,,CITY ; PE£ 5u . . Pv'1P 1 ,,,0, J Cu ,.Fz: PER -- '5EC~ .. - L --· _:_ 17.2 I • i :Z?4 ,FEFiT ·-- ·• ---· -------- -- -- ---- - PvM4 IIERJJ = ' 3Jt, • FEET i Voibi£ - •·1 £rr1c1c1t1c j W.H.:P F',H.P. -t,J Bt,.-11-1{, ; • • 'JS-. "f 10 ,38,17%, 3'1.3 64.817,, --- 78 1g. 62 ho d1rec ion-or the v locit ed 1 $.on no des4- n tin the v otorfJ . FIG.5Z 1 • V loeit t l ' how the 1 erent Pi tot and 47 re olotted the olute . ve?' ge a ou.rve ot the t er s• 3 ngl e sured tt Att. m aur d r bsolu e gles h on 1g. 53 is the n le ros t • inner e.s 1dth oft 1 er . Ci non- 1 ection 1torm, ngle the hile th d1r ot1on is uc A" 1a more unlfor t light n t 79 high and low pump ce.pacities. !!'1.g. 54 shows the ave1~age di:r•eotion of the relative exit velocity vectors at the different Pi tot stations. All points but one- show a relative exit angle less than the vn:ne $Xit angle, that is, the r~eltltive exit velocity is not following the va ne tangent. Considering this mn tte:r• of r·eJu tiv~ ex:i t directions, th.ere is a r;9ma rlmbl1i &.gr~~me:nt between the observ~d values and the eonclusiona reached by h:~of • Ii .L .De.ugherty in his book,'1Centrif'ugal PumpsH . On page 81 of his boolc he atHtes (s.r1"ived nt by inductive reasoning} tht1t the difference between the vane angle and th~ &otual relr1. tive exit angle 1♦ • • • nmy d.if.rer by from five to ten de-gre es ••• " • Fig. 54 shows the. t for no~~n.?.. l CE.tpaci. ty the diff·erence in angles vms nine degrei!ls. An unpublished oa.leulation m&de by Prof. Dt1.ugherty s h owed a elos.e rn.greement. Using his theory, he rnnde calcule.tions for a pump whose specific speed was very close to that of tbte Worthington pump. 'the ealeula t0d rttlv. t:S.ve 6Xi t nngles for low, normi.:tl, Hnd high capacities e.greed closely with the observed va lues shown on Fig. 54. 'I'he range of agrt1temen.t wt::1e someth.ir1g like one degree. 'l1hie agreement betwe~n theory a nd experimei1t s peHlis well f'or both is?ntirely independent r11ethods of o. ttaeking this problem of pump flow. -30 I I. I I I .. I! . ; . I I 82 BIBLIOGRAPHY 1~ Kucharski, "Stromungen einer reibungsfreien Flussigkeit be1 Rotation fester Korpern, Munich and Berlin, 1918. 2. Busemann, ttDas Forderhohenverhaltnis radialer Kreiselpumpen mi t logari thmisch-spiraligen Sehaufelen", Ztsch. f. angew. Math. u. Mech., Bd. 8, 1928, s. 372. 3. Schultz, "Das Forderhohenvernaltn1s der Kreiselpumpen fur die ideal und wirkliehe Flussigkeitn, Forsch. Arb. Ing.-Wes. Ht. 307. 4. Sorenson, "Pontentialstromung durch rotierende Kre1selrader", Ztschr. t. angew. Ma th. u. Mech., Bd. 7, 1927, s. 89. 5. Uchimura and K1to, "On potential flow of water through centrifugal impeller", J. of Fae. of Engineering, TSkya Imp. Univ., Vol. 19, No. 8, 1931. 6. Pfleiderer, "Die Kreiselpumpen", Berlin, 1924. 7. Spannhake, "Hydraulisehe Probleme", :Metteilungen des Institute f'ur Stromungungsma.sehinen der Technischen Hochsehule Karlsruhe, Heft 1, 1930. 8. Fischer and Thome., A.S.M.E. Transactions, 1932. 9. R. L. Daugherty, "Centrifugal Pumps", 1915. 10. Francis, ttLowell Hydraulic Experime-ntstt 11 1909. 11. Thoma, "Die Versuchsanstalt f"ur Wasserturbinen in Gotha", 1918. 12. Oertli, ff ... Untersuchung der Wa.sserstromun.g dureh rotierendes Zellenkreiselrad", Zu:r:teh, Dessert., 1923. BIBLIOGaAPHY Cont'd. 13. Stiess, "Uber die Relative-·S tromung in einem PwnpenLaufrad von Grossem Radien-Verhaltni~n, Mitt. d. Inst. f. Stromungsm. d. Tech. Roehs. Ke.rlsM$,e, Ht. 3, 1933, s. 77. 14. _Closterbalfen, "Hilfsmittel zur Beobaehtung und Messung an umlaufenden Kreiselraderntt, Forsehung, Berlin, January, and February, 1931. 15. l"endo, "Exper:I.mental Researches of Turbine Pumps", Rep. of the Yokoha~ Tech. College, No. 1, 1930. 16. Kasai, "On the Exit Velocity and Slip Coefficient of Flow at the Outlet of the Centrifugal Pump Impeller, with Some • References to the Characteristics of the Pump" • . Kyushu Imperial Univ •. Memoirs, Japan, 1936. 17. R. C. Binder, M.S. Thesis, California. Institute, 1933. 18. "Air Forces on Circular Cylinderstt, Dryden - Scientific Paper No. 394, Bureau of Standards, 1920. 19. Fechheinier, "Measurement of Sta.tie Pressure", A.S.M.E. Transactions, 1926. 20. E. R. Lockhart. M. S. Thesis, California Institute, 1934. / / . ,. 21. Th. von Karman, "Uber Lam1nare und Turbulente Reiburg", z. angew. Math., Mech., vol. 1, 1921. A.Cl.oaterhalfen, ttversuche an ei11er Sehs.ukreiselpumpan For,schung.Berlin, July 1931  4. i Fnac 66 - : Across VonuTe “Ppsiripy F VER: file Zo. xe ANCE M? = LM PELLE! A, LE AIBIOL TE VEL eal | + | : i i { : + han BEEN fe 4 { 2 (ORL EL OCIS OF ENT i ‘ Fs PIBSPOLUIE. cae WA. IMPELLER i i Hite Et ¥ is) ie Ete eee ee Wes en Pe eee ese Pat tad ek Ee EG a0 Ee eae ee TRS eee et tee cede Hd et te a ee ede cee dE SSE esc ed ta ae Wee ul tet an er eee et el Pee ep tO te Pete en Teele : a Sa AES ae SE a era ee aes Esa em 2 ASE a ae ee La ere ea Deere ES 2 ee Reet ee i it iw AS i : f T + SS d nee eben Se eas eek See ee eee ee ee et ed eee eee oes eeeices tga iano BEATER IE Grr GielGaa ACR ee u 4 Db i it Esl 2 4 | t ‘| Meabs #aelecer 1 ae WV nh poe nceay | fi _. | | FosTion| 4A ae “WA, TANGENT >| AAI AANWAAY Ej he by Fal LUTE Veocry ) at i CH) (PONES LOLS A) a8 oo ABSOLUTE 4 ¢ fei! f | ANG af (12 MPELLE, : TANGENTIAL ABSOLUTE ELOC, svat? oC hee 50. 20 2D. 1). N 10 fuerte + 29 3o, 2 et t se te ieee ce Sheed i 4 i ee Ge i i ' pee pal ie ine el soft hii fee be ei 1 a ne a rae i Hod PS Roe ae : 9 (Sito! Siemmoen, aa al f 5 Piso eed ete a L i i ti i °. | i Fal a { L ! i A ey =~ as ee co Ni yo a Sues) a : | (nies eee Guat ae eens eee iy ae > iL 2 BSS elt 9 cee ee ee a rf eater er ee tee Ue tel ee eC ee et ie ee ee Qi il an Hy Ss i ee eee ew : Seed ae i a ne & oie Sa eee a nia a al as SRG | i | Hata ea a rains cate ass i i E cat sii i cu NR if a Saas ey Bea He 6 SOQ AUS is ae a ae ae i ad Sa LAA, COsTE paiBe IBSOLUTE VELOCITY: Poss tow. Cs MEELLER | FERIPHE 3 H ABSOLUTE WELOcT [. Rees with IMPELLER TANGENT _ Pos/tion B. Se ie | | Postion A i 42. oO a 4 NG EMTIRL “COmRONENT — ' IELOCITY | PEW ER TANGENTS |b ITH INGLE WITT. ay ae 4 oe OM LE 30-2