Research On Modeling And Control Laws For Variable Cycle Engine

In the field of current military aviation, along with the expansion of aircraft fighter envelope andcomplexity of flight misson, tradictional fixed geometry or only few adjustable geometry enginescould not meet the lower specific fuel consumption and higher specific thrust requirements for thepowerplant.According to foreign research, the variable cycle engine is an ideal powerplant for nextgeneration multi-role fighter, and it is more preponderant in accommodating combined mission flight,based on above consideration, in this article, the double bypass variable cycle engine was taken as theresearch object, the research on modeling and preliminary adjustment schemes in mode transition forvariable cycle engines was studied.Firstly, a steady and transient component-level methmatical model of a double bypass cycleengine was built up, considering the influences of variable inlet guide vane and variable turbinenozzle area on component characteristics of compressor and turbine. Besides, the effect of the modeselector valve area on deputy bypass inlet air flow was also considered during the modeling process ofdouble bypass variable cycle engine. The typical two operation modes steady states and modesswitching process were simulated.Secondly, the influences of readjusting the geometric parameters such as the variable guide vanesof fan, CDFS and compressor, variable low turbine throat area, the rear variable area bypass injector,and variable nozzle throat area on engine performance had been researched; in two typical operationmodes, the engine performance (thrust and economics) was improved by adjusting multi-components.Finally, mode transions between single bypass mode and double bypass mode were studied;under the given preliminary open-loop adjustment schemes, mode transions could be accomplishedsmoothly and safely, since the engine performance parameters (rotor speed, turbine inlet temperature)didn’t exceed limit, the engine didn’t surge, and the maximum fluctuations of low and high pressurerotor speeds were less than1.5%.