Real-Time Jet Engine Performance Analysis System With Compressor Surge and Turbine Choked Flow Detection Functions

Abstract This paper introduces an analysis system for the performance and thermodynamics characteristics of a jet engine in real-time. Parameters such as air mass flowrate, fuel to air ratio, temperature before turbine are calculated continuosly in real-time. Basis functions of the program are calculations of isentropic exponent and specific heat coefficients according to air temperature and fuel to air ratio. Energy conservation calculation process and shaft power balance calculation process are the keys to determine all thermodynamics parameters. These processes ensure that analysis results are consistent, precise and reliable. Engine performance charts such as Combustion efficiency, Compressor efficiency, Turbine efficiency, Thermal cycle, Compressor map, Turbine map, Brayton cycle are presented instantaneously while the engine runs. Based on these real-time parameters and charts, compressor surge detection and turbine choked flow detection functions are developed. Compressor surge is detected by the oscilation of air mass flowrate. Turbine choked flow is detected by a sideways or downward movement of turbine mass flowrate reduced when turbine pressure ratio increases. The system has been applied to analyse data from several axial compressor turbojet engine prototypes and it is capable of running online while the engine operates and offline to analyze test data from a text file. A summary report on thermodynamics and performance of the engine can be created after the end of the test. This report can help analyze the performance of each component in the engine at different operating points to detect abnormalities, or help improve engine efficiency.