Off Design Performance Analysis of a Turbo Shaft Engine

Abstract

The off-design performance of a gas turbine engine is strongly influenced by the characteristics of individual components. It involves the interplay of a large number of variables and would require a detailed computer code. In this paper, an effort is made to predict the influence of performance characteristics of individual components on the off-design performance of the engine. For this purpose, a computer code is developed with necessary iterations and convergence criteria. Parameters are estimated with respect to speeds ranging from 39500 rpm to 50500 rpm for a typical turbo-shaft engine with free power turbine. The effect of altitude on these parameters up to 6 km is also studied. Variation of specific heat and enthalpy with respect to temperature and fuel to air ratio is considered to estimate the performance calculations more accurately and to simulate a real engine behavior as close as possible.