Modeling and Closed-Loop Transient Analysis Method of Large Bypass Ratio Turbofan Engine

Abstract

As the core aerospace power unit, the high-bypass two-spool separate-exhaust turbofan engine, a typical aerothermodynamic coupling system, exhibits strong nonlinearity within the flight envelope due to dynamic changes in environmental parameters and operating modes, with transient control being a research difficulty for involving multi-steady-state switching and fault risks. This paper built its component-level model via the analytical method based on aerodynamic/thermodynamic principles, solving nonlinear common working equations with the Newton-Raphson method; validated against GasTurb, 6 key steady-state parameters had relative errors <2%, and dynamic errors <1.5%. A closed-loop controller integrating steady/transient control and anti-windup was designed: steady state used PI parameter interpolation to control corrected fan speed; transient state adopted high-low select logic to limit fuel commands and coordinate VSV/VBV; output regression suppressed integral windup. Tests showed steady-state tracking error <1% with 2%-3% overshoot, transient rise time ~8s with error <1%, and key parameters safe, supporting engine performance optimization.