Variable geometry characteristics research of double bypass variable cycle engine

A mathematical model is established for calculating double bypass variable cycle engine (VCE) performance, which achieves engine/inlet mass flow matching and realizes dual parameter control law and the simulation of variable geometry components performance. Variable cycle engine can work in single or double bypass mode, under the conditions of maximum thrust or minimum fuel consumption, with or without afterburning. According to the engine operation, four typical flight conditions including takeoff, subsonic cruise, supersonic cruise, acceleration and climb are chosen. The control law of ten adjustable geometry parameters and their influence on variable cycle engine's installed performance and stability are analyzed of each flight. The results indicate that compared with fixed geometry variable cycle engine, the installed specific fuel consumption of variable geometry variable cycle engine decreases by 3% and 30% in subsonic and supersonic cruise respectively, meanwhile the installed thrust increases by 42% in acceleration and climb, and sufficient surge margin of engine can be ensured.