Numerical Investigation For Vortexes And Aerodynamic Heating Environment In Transverse Gaps On Hypersonic Vehicle

Hypersonic reentry vehicles, such as space shuttle and X-37 B, are subjected to severe aerothermal environment while they maneuver to reentry the earth`s atmosphere. In order to accommodate the thermal expansion, gaps are reserved between TPS tiles. Besides, the gaps are also necessary for some flight maneuvers like angle changing of rudder reflection and aircraft parts poping-out.With the existence of gaps, aircraft surface flow condition changes a lot. Firstly, there would be local high heat flux at the gap entrance because of the boundary layer separation-reattachment; secondly, the shock wave may appeared at gap entrance in some conditions; in addition, vortexes would be induced in gaps. The vortexes could bring a lot of heat into gaps and significantly enhance the convective heat transfer. The thermal radiation would be blocked because the gaps are very narrow. As a consequence of that, the wall temperature could rise very easily, which leads to relatively severe ablation. Therefore, it is very important to study the gap flow structure and how the inflow/geometric parameters affect the vortexes and wall heat flux.The space powers deeply research on the gap flow. During the development of space shuttle, for example, the United States invested lots of manpower and material resources to perform the experiments on aerodynamic Heating Environment and thermal structure of the TPS gaps. These early researches mainly rely on ground experiments, which cost long operation period and high fund. Trying to overcome those drawbacks, a numerical simulation research of transverse gap has been conducted via self-developed software.Firstly, the achievement and drawbacks of gap flow research in mechanism analysis, experimental measurement and numerical simulation are introduced. Aimed at these drawbacks, we bring the conservative enthalpy correction into the van Leer flux-vector splitting method. So the resolution of the gap calculated flow field is improved greatly. Next, we verified the validity of the methods and found that capturing the vortexes reasonably is significant to simulation the heat flux.Then, the gap flow mechanism is analyzed. Based on the infinitely long transverse gap model, the formation, development and dissipation process are analyzed from the standpoint of vorticity.Based on the analysis of last chapter, we focus on the effect of inflow parameters and geometric parameters on gap flow, which elaborates the variation regularity between vortexes and wall heat flux with inflow Reynolds number, inflow Mach number, inflow attack angle, gap depth-to-width ratio and edge radius. And the criteria for judging whether the number of vortexes is equal to the depth-to-width ratio are given. The regularity can provide a reference for thermal-protection design.At last, a review about the work in this thesis is made, the drawbacks of this thesis and the direction for further study are also given out.