Study On Wide Speed Range Aerodynamics/Propulsion Integrated Coupled Modeling Of Combined Propulsion Vehicle

Combined propulsion vehicle is a kind of vehicle which in general propelled by combined propulsion engine.This kind of vehicle characterized by wide space range,wide speed range,multi-mode engine and aerodynamics/propulsion integrated design,and result in the model of combined propulsion vehicle with features of strong coupling and nonlinear.The developed models include experiment based,CFD(Computational Fluid Dynamics)based and physical mechanics based model have the deficiencies of high object dependence and incomplete wide speed range engine model.And,the experiment based and CFD based models are too time consuming to satisfy the large number of concepts decision,optimization and modification in the preliminary design phase of combined propulsion vehicle,Therefore,the physical mechanics based object independent wide speed range aerodynamics/propulsion integrated coupling model with the accepted accuracy and robustness was draws the focus in the work.In the context,the characteristics of supersonic/hypersonic aerodynamic models were analyzed,the combined strategies and matching methods were proposed,and the wide speed range aerodynamic combined models and aerodynamic forces preliminary evaluation platform were developed.Furthermore,the mode transition strategies was carried out,the multi-mode engine model and propulsion performance evaluation method were established against the multi-mode propulsion system of combined propulsion vehicle.Moreover,the coupling computational method assembled inner/outer flow field division principle and discipline data relationships were carried out,and the wide speed range aerodynamics/ propulsion integrated coupling model was built.At the last,the integrated coupling model was used to analyzes the coupling characteristics of a combined propulsion vehicle.According to the results of coupling characteristics,the mathematical models was carried out and the multi-discipline applications against to trajectory and control were performed.The innovations concluded in the context were shown as below.(1)The combined strategies and matching methods were carried out,and the pressure and friction combined models along streamline and aerodynamic forces preliminary evaluation platform(AFPE)were developed,with regard to combined propulsion vehicle.The comparison of the results of combined models and AFPE with the results of CFD and experiments agrees that the combined strategies and matching methods not only extend the application range,but also ensure the root-square-error less than 3% while the time consuming less than 100 s.(2)The mode transition strategies of wide speed range engine of combined propulsion vehicle were carried out,which combined with the models of ejector,dual-mode scramjet and rocket,and the propulsion performance evaluation method were established for multi-mode engines.Among these models,the comparison between the dual-mode scramjet model and experiment agrees that the root-square-error of pressure distribution and axial thrust less than3% and 6%,respectively.The mode transition strategies of wide speed range propulsion system can ensure the smoothness and continuation of thrust along all of the trajectory of the combined propulsion vehicle.(3)On the basis of the analysis of aerodynamic and propulsion performance of combined propulsion vehicle,the coupling computational method combined inner/outer flow field division principle and discipline data relationships were carried out.The aerodynamic and propulsion performance was evaluated separately,under the inner/outer flow field division principle.Then,the inlet performance governed by aerodynamics and nozzle performance governed by propulsion system were evaluated from head to back by using the independent inlet and nozzle model,under the discipline data relationship requirements.The analysis against the typical combined propulsion vehicle agrees that the integrated coupling model based on the coupling computational method can draw the aerodynamic performance in the wide speed range correctly.(4)The wide speed range mathematical models were carried out based on the coupling characteristics of aerodynamic/propulsion,and the research on multidisciplinary applications were put forward.On the one hand,the results of analysis of aerodynamics/propulsion coupling characteristics indicate that the nonlinear strong coupling relationship exists between aerodynamics and propulsion,the linear variation is only the linear projection of high order variation.On the other hand,the seeds of major influence functions were drawn out based on the coupling characteristics,the wide speed range mathematical models were extracted by using the intelligence algorithm,and multidisciplinary applications research were put forward which was used in trajectory optimization and control system design.