Performance simulation of large civil aircraft auxiliary power unit

By analyzing the structure and aerothermodynamics processes of the typical auxiliary power unit (APU),this paper used object-oriented technology and C++ program to design the classes of APU components.In order to simulate a 150-class civil aircraft APU model,instances of the component classes were assembled.According to the APU operating conditions,the thermodynamic and off-design performance calculations were completed,the design state performance and operating envelope about aircraft environment control and main engine start models,as well as altitude-speed,temperature and load characteristics,were obtained accordingly.