Heuristic deepening of aero engine performance analysis model based on thermodynamic principle of variable mass system

The variable mass system (VMS) model for aero engine performance analysis takes into account the variable mass characteristics attributed to the gas compressibility and mass coupling. In order to accurately predict the performances of aero engines under a variety of drastic changes of working conditions caused by the process of rapid acceleration, high power output and high maneuver, the performance analysis model based on VMS is optimized. The computational efficiency and applicability are improved by modifying the solution methods of variable mass terms and governing equations, which can elaborately predict the transient performance compared to conventional models. To verify the accuracy of the improved VMS model, the simulation results are compared with the engine test data. The relative error of the simulation results for the VMS model is reduced from 11.8 % to 7.8 % compared to conventional model, and the computational efficiency is increased by 32 % without loss of accuracy. Simulations have been conducted for a series of transient operating processes, including acceleration process, power extraction process and maneuver process. The simulation results reveal that the mass variable features become obvious as the volume of turbofan engine increases and the time required for the variable operating condition decreases.