Study On High Stealth Thrust Vectoring Nozzle And Afterbody/propulsion Integration

The next generation of fighters requires that aircraft equipment satisfy both high thrust,low fuel consumption,high stealth and high maneuvering propulsion systems.Variable cycle engine(VCE)could meet these demand,exhibit well adaptability and versatility,thus is an ideal candidate for next generation fighter.Exhaust system is one of the core components of the engine,and the new variable cycle engine normally use unconventional exhaust system.In this thesis,the high stealth exhaust system of adaptive cycle engine is taken as the research object.The exhaust system model was constructed.The numerical simulation software CFD is used to study the flow characteristics of the exhaust system.Preliminary exploration of thrust vector realization scheme and aerodynamic performance of aircraft / engine Integration.First of all,taking the double-S-bend C-D nozzle(double S nozzle)as the research object and constructed the high stealth double S nozzle with single flow path geometric model.Studied flow field structure and aerodynamic performance parameters on ten groups of double S nozzles with different geometrical design parameters,and through the comparative analysis of aerodynamic performance parameters,select a group of the best overall performance of the model as the final single flow double S reference nozzle.Studied the rule of the reference nozzle area,flow field structure and performance of double S nozzle after adjustment under the condition of afterburner open.Secondly,due to the multi-mode working characteristics of adaptive variable cycle engine,thus the exhaust system also has the characteristics of multiple flow.In this paper,the double S nozzle has the working status of dual flow.When the adaptive cycle engine is in three bypass mode,the outer bypass of exhaust system open,at this time,double S nozzle is in double flow mode.To realize the opening and area adjustment of the outer bypass,the reference double S nozzle geometry adjustment scheme was studied.The flow field characteristics and performance of the double S nozzle under double flow mode are obtained by CFD simulation.Based on the reference nozzle and the area adjustment,studied the thrust vector function to realize the aircraft high maneuverability.Double S nozzle due to its two operating modes: double flow mode,single flow mode.Based on the basic single flow double S nozzle,the geometric expansion of the nozzle was carried out.The range of thrust vector angle of single flow nozzle,flow field structure and aerodynamic performance were studied.After the dual flow path nozzle is actuated,the core flow is covered by the outer flow path air flow,which can reduce the influence of geometric deflection on the core flow.Therefore,the study on the thrust vector of double flow nozzle is carried out.The results show that with the increase of the downward deflection angle of the S nozzle in double flow mode,the attachment of the core flow may occur,and the flow loss of the nozzle is larger.Finally,under the guidance of the airframe/ engine integrated installation principle,the double S nozzle installation and the integration of the fighter model are completed,and analyzed the mutual interference between the exhaust system and the aircraft under different flight conditions.Under various research conditions,the interference between the aircraft and the exhaust system is greater at subsonic speeds and less disturbing at supersonic speeds.