The Flow over a Body in a Choked Wind Tunnel and in a Sonic Free-Jet

Author: Marschner, Bernard Walter

Year: 1954

Degree: Dissertation (Ph.D.)

Advisor: Guderley, Karl Gottfried

Committee Member: Unknown, Unknown

Option: Aeronautics; Mathematics

DOI: 10.7907/P4DG-RV54

Abstract

The pressure distribution over a double wedge airfoil under free flight conditions with Mach number one is compared with the pressure distribution over the same airfoil in a choked closed wind tunnel and in a sonic free-jet.

The computation is carried out as a development with respect to a parameter which indicates the deviation from free flight conditions with Mach number one. The results are of interest for the question of wind tunnel wall influences. It is found that the deviatiors of the pressure distribution for a sonic free-jet from the distribution in an infinite air flow are somewhat larger than the deviations in a closed wind tunnel under choked flow conditions. For a specific exam of a wedge of a length of 13% of the tunnel height and a thickness ratio of 10%, the deviation of the pressure distribution does not go much beyond the usual experimental scatter.

The results are quite encouraging for the application of closed throat wind tunnels in transonic testing although the axial symmetric case may not show entirely the same desirable behavior.

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