Theoretical Investigation of Acceleration of a Turbojet Engine

Authors: Satterfield, Loys Malcolm; Wheatley, John Paul

Year: 1947

Degree: Engineer's thesis

Advisor: Rannie, W. Duncan

Committee Member: Unknown, Unknown

Option: Aeronautics

DOI: 10.7907/N3NM-X518

Abstract

The failure of turbojet aircraft propulsion units to accelerate rapidly to high thrust operation when emergencies arise in slow speed flight has restricted their use in aircraft applications, and has also concentrated considerable attention upon their acceleration characteristics in an effort to produce better results. This thesis presents a method of computing the acceleration of a particular turbojet by making use of complete performance curves of the component parts of the turbojet.

The method presented here does not permit computation of the acceleration for a particular operating condition as determined by those variables usually considered independent; namely, (1) Flight conditions of velocity, density, pressure, and temperature, (2) Engine rotor speed (3) Fuel rate of flow, and (4) Tail cone area ratio. Computation using these four independent variables was originally attempted in preparation of this thesis. However, extreme complication in the computations dictated that turbine inlet temperature and air mass rate of flow, which are normally dependent variables, should be considered independent. Fuel rate of flow and tail cone area ratio are therefore considered dependent. Therefore, in order to match a particular operating condition it is necessary to make a family of computations for various turbine inlet temperatures (constant for each set) over a range of assumed air mass flows.

Computations have been performed for the Westinghouse X19B axial flow turbojet to illustrate application of the method and to show qualitative and quantitative effects of variation of tail area ratio, at two different turbine inlet temperatures.

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