An Exact Derivative Based Aero-Engine Modeling Method

Abstract

Derivatives are involved in getting the Jacobian matrix for the component-level model (CLM) and the state-space model of aero-engines. However, the relationships among the variables of aero-engine are complex, and it is difficult to get analytical derivatives, which results in that the approximate derivatives are calculated by finite difference approaches and the real-time property is constrained. Thus, an exact derivative-based modeling method of aero-engine, which transforms the problem of derivative calculation to the problem of differential calculation with a chain-derivation method, is proposed. Also, the differential calculations can be executed along with the component models, and no extra aerothermodynamics calculation iteration is required. The proposed method is implemented in the steady state and transient-state calculation of the CLM, so the real-time property of the model is improved. Compared to the conventional models with centered difference method, the total time consuming of the CLM built by proposed method can be decreased more than 54% and 55% in the steady state calculation and transient-state calculation, respectively.