Real-Time Dynamic Simulation of Single Spool Turboj et Engines

Abstract

A hybrid integration method is proposed in this paper for the real-time simulation of single spool turbojet engines. The nonlinear dynamic model of the J-85 turbojet engine is developed first. Three types of integration methods, including explicit integration methods, implicit integration methods, and the proposed hybrid integration method, are used to integrate the dynamic model. Simulation of the model by explicit integration methods fails to reach real time, since the stiff characteristic of the engine model requires small integration step size to maintain stability. On the other hand, al though use of an implicit integration algorithm can enlarge the step size, extra function evaluations are needed to calculate the system Jacobian for the Newton-Raphson algorithm, and the simulation still cannot reach real time. The proposed hybrid integration scheme uses an explicit method to in tegrate the non-stiff part of the system, and an implicit method to integrate the stiff part of the system. Real-time simulation can be achieved by using the proposed hybrid scheme.