Numerical Investigation For Aerodynamic Heating Environment On Leading-edge Gap Of Hypersonic Vehicle

With the development of hypersonic flight technology, the design of thermalprotection system, which is essential and vital for vehicle with long flight endurancein the atmosphere, has become one of the key research contents. These vehicles,especially at the nose and the small-sized wing-leading-edge, usually have verycomplex thermal protection system because of the serious aerodynamic heating. Atthe wing-leading-edge, gaps between the protection elements that may absorbthermal expansion and reduce thermal stress are introduced and designed in order toavoid the thermal stress destruction in the protection elements caused by theextremely serious aerodynamic heating. The gaps between panels are obturated bythe associated T-seal at the design condition, whereas the T-seal may fall off or breakdown and the high temperature gas may crush into the gap during the actual flight.Therefore the flow field characteristic and heat-flux distribution for this kind ofspecial longitudinal gap flow is investigated in this paper.The thesis contains five chapters. The first chapter gives a brief introduction ofthe development of the hypersonic vehicles and an expatiation on the longitudinalgap at wing-leading-edge, the research status and results in the correlative field inand abroad is also introduced.In the second chapter, the governing equations, numerical methods and avalidation case about two-dimensional flow over circular cylinder are presented. Inthe numerical methods part, the van Leer flux-vector splitting method is used forcalculating the inviscid flux and MUSCL method with Van-albada limiter is adoptedfor the reconstruction. The Navier-Stokes equations are solved by using afinite-volume solver and LU-SGS implicit method is used for time integration.Chapter three is the key content of this paper. At first, the design process andgrid generation for the gap model are presented. Then by analyzing the flow fliedstructure and heat flux distribution, the generation and development of the vorticesand the peak value and influenced area in the high heat-flux zone are obtained. Thecorresponding relations between the vortex motion and heat-flux distribution are alsointroduced and explained via simulation results.The fourth chapter follows on the previous chapter and investigates the effectsof gap aspect ratio and angle of attack to the heat-flux distribution. The first part ofthis chapter is mainly about the variation of heat-flux distribution with the gap aspectratio increasing. The analysis focuses on the relation between surface heat-flux andvortex motion. With the angle of attack increasing, the second part gives the variation of heat-flux distribution on the circular section and straight section aroundthe gap.The final chapter is the conclusion. The summery of the research in this paperand the outlook of the future work are presented.