Research On Component Level Modeling For Variable Cycle Engine

With the performance of aircraft growing,conventional aircraft engines could not meet the requirements of military aircraft.In recent years,for the sixth generation fighter,it should have a shorter takeoff and landing distance,a longer flight envelope and combat radius,a stronger capability of supersonic cruise.In this case,variable cycle engine shows greater potential than those conventional designs.Firstly,the history of study on variable cycle engine and current status of variable cycle engine and the future development trend of the variable cycle engine are introduced.Secondly,based on Matlab/Simulink,a component-level model of novel cycle engine is built using the volume dynam ics,considering the equat ions of gas dynamics and the match between relations.The model is able to operate on both steady and transient modes.Furthermore,mode selector valve and second bypass are added based on the novel cycle engine in the last chapter to get a variable cycle engine model,which possesses two bypasses.The effects of variable inlet guide vane on component characteristics of fan and compressor are considered.The model also divides the fan into fan hub and fan tip.The two operation modes are simulated.Also,based on the established model,the effects of regulating the geometric parameters on engine performance such as the vane of mode selector valve,the variable guide vane of fan and compressor,nozzle throat area have been studied by steady state simulation.The mode transitions between two typical operational conditions are simulated.The nonlinear model structure of NARX,a nonlinear and nonmathemat ical model is ident ified by the data of the operation of model that based on the variable cycle engine in the last chapter.An optimal ident ified model is selected by referring to the evaluation of AIC and Best Fit and then an comparative analysis is performed,and the results show that the identified model is suitable for nonlinear modeling.