Variable Geometry Engine Steady-state Performance Computing Research

The variable geometry and variable cycle engine (VCE) is an ideal propulsion installation applied to the Forth mixed mission (supersonic/subsonic) aircraft. By adjusting many variable geometry components of the engine, bypass ratio can be changed during large range (the most 0.25 of military fighter). The high specific thrust characteristic of turbojet engine and the low specific fuel consumption characteristic of the turbofan engine can be realized during different flight phase by the usage of VCE technology.By using HARIKA algorithm, the characteristic of a high-pressure compressor is calculated at different installation angle of the inlet guide vane and the stator vanes; The characteristics of a high-pressure turbine and a low-pressure turbine are simulated at different installation angles of the guide vane based on Ainley method. And those characteristics of compressor and turbine are put into the steady-state design and off-design performance program of augmented turbofan engine, to calculate the influence of the geometry changing of single component on the performance of engine. These variable geometry components include high pressure-compressor, high-pressure turbine, low-pressure turbine, inlet area ratio of mixer and main nozzle throat area. The results of calculation show that the adjusting of low-pressure turbine and mixer has a remarkable effect on the performance of engine and bypass ratio. The influence of changing single component geometry on the engine performance depends on the geometry of other components or the structure of engine. At last, the effect of adjusting multi-component on improving the engine performance (including thrust, economics and stability) is proved.