Research On The Design Of Structure And Thermal Protection System For Combined-Cycle Propulsion Vehicle

Combined-cycle propulsion vehicle is subjected to complex thermal and aerodynamic load during flight,and the design of structure and thermal protection system(TPS)is a key technology for the conceptual design.A preliminary design process for rapid design of TPS,optimization design of wing structure layout,optimization design of the structure system was presented in this paper,and the concept of structure and TPS was obtained.The work of this paper is finished in the following aspects:(1)The aero-thermal environment of combined-cycle propulsion vehicle was analyzed,and an initial design scheme of TPS and structure was obtained.The coupling relationship among different disciplines was analyzed under the environment of multidisciplinary design optimization,and the optimization design process of structure and TPS was established.(2)With the requirement of TPS for combined-cycle propulsion vehicle,a rapid design method of TPS was developed.The aerodynamic heating environment was obtained by the engineering method,while an aerodynamic heating database was obtained by the spatial interpolation method.With the reference of the TPS concept of typical combined-cycle propulsion vehicle which are already exist,the TPS layout of combined-cycle propulsion vehicle studied in this paper was generated,an optimization problem with mass per unit area of the TPS as objective function and the temperature limit as constraint was solved and the optimal mass of TPS was obtained.The optimal mass of TPS is 7102.3 kg.(3)With the requirements of the optimization design of wing structure layout,an two-level hierarchy optimization strategy was developed.In the first level,an topology optimization was used to determine the main load-transferred path,and in the second one a hybrid optimization with both shape as well as size design variables was used to obtain the precise position and the optimal size.In addition,the selection of material for different component was considered in this paper,and an method was proposed to solve the optimization problem of material selection.The optimal material combination of the wing was determined.(4)Based on the homogeneous method,an equivalent approach was developed and the accuracy of the proposed equivalent approach was assessed.Based on the equivalent model and topology optimization,the finite element model was established and transient thermal analysis as well as optimization design was solved to obtained the optimal mass of the combined-cycle propulsion vehicle structure.This study can meet the design requirement of structure and thermal protection system of combined-cycle propulsion vehicle,and provide a complete process of structure and thermal protection system design in conceptual design phase for this kind of vehicle.