Study On Aerodynamic Characteristics Of High Stealth And Airframe/Propulsion Integration Exhaust System Of Variable Cycle Aero-engine

The next generation fighterdemands upgradecombat abilities,therequirements of propulsion systemincludehigh thrust、lowspecific fuel consumption、high stealth.Variable cycle engine(VCE)could meet these demand,exhibit well adaptability and versatility,thus is an ideal candidate for next generation fighter.In this thesis,a kind of S-shaped exhaust system model of adaptive cycle engine was constructed,the performance and flowfields of these S-shaped nozzles and its integrated with fighter were studied.First,based on the configuration of ACE which developed by GEAE,a design point aerothermodynamics calculation model was built.Design parameters of different component parts were set.With different bypass ratio,the characteristics of aero-engine and flow parameters of specific cross-sections were obtained,provides datas for the following research.Second,in order to meet the next generation fighter for high stealth performance requirements,designed 6 groups of high stealth S-shaped nozzle model,by the method of CFD numerical simulation,obtained nozzle performance parametersand flow field structures of different nozzle models.By comparing the nozzle performance parameters,combining with the requirements of nozzle installation,one group of nozzle was selected,and optimized the jet angle of the chosen nozzle model.Selected the optimized nozzle model as basic nozzle model for further research.Using the basic nozzle model,double stream and triple stream exhaust system of ACE were built.The flow characteristics and nozzle performance were studied.Nozzle performance parameters of double stream and triple stream exhaust system were lower than basic nozzle model,mainly due to the loss caused by mixing of high speed multi stream and following wave system.The injection ratio of double stream exhaust varied in wide range,and it could adapt to all kinds of different patterns and engine regulation.When the external bypass total pressure ratio was too small,gas in external bypass was blocked.Setting reasonable external bypass exit position,and proper total pressure ratio of internal and external bypassor bypass ratio,would make double stream and triple stream exhaust system work on adjusting operation state of engine and achieve thrust augmentation.Last,drew a conclusion of the principle of exhaust system installation,meeting the demand of airframe/propulsion integration.Following the principle,a research airplane was constructed and high stealth S-shaped nozzle was installed.Analyzed the aerodynamic performance of airframe/propulsion with exhaust system installed and uninstalled,under different flight mode.In the state of typical and important flight regime,no remarkable influences arose,indicated the effect integration of high stealth exhaust system and airplane.