Reentry Body Surface Fluctuating Pressure Environment Analysis And Forecast

Hypersonic vehicles in flight are subjected to some critical loads, which have increased the complexity of their structural design. The most important one is the high temperature environment. The second is the effect of the fluctuating pressure generated by the hypersonic turbulent boundary layer and its interaction with accompanying shock system. Besides causing potential structural failure, the fluctuating pressure loads can also induce danger aeroacoustic environment to the crew or equipments on the vehicles. In order to provide database for structural fatigue analysis, the properties, also the causes, of the fluctuating pressure environment are analyzed based on the physical flow phenomenon, the stability theory and the theory of turbulent flow. After analyzing the existing techniques for the prediction of fluctuating pressure, we conclude that the combination of numerical simulation with the empirical models, which are based on the experiments, will be a more effective and more economical method with the advancement of the computer performance and the improvement of the reliability and the accuracy of the numerical technique. Based on this conception, numerical studies are conducted to provide necessary flow field data for the fluctuating pressure models through solving the 3D compressible mass weight-averaged Navier-Stokes equations. The time and space second order NND scheme is adopted to discrete the equations and the B-L turbulent model is used for the turbulent flow field simulation. Based on the flow property analysis and the numerical results, different engineering models are adopted to predict the fluctuating pressure loads on the cone surface and the root area around the control panel respectively. For the cone surface area, some reliable models from Ref [4] are utilized and a series of reasonable results are got compared with wind tunnel test data. For the root area around the control panel, a model is constructed by correlative analysis technique based on some wind tunnel test results and the partition property of the flow field in this area. After serious reliability check, this model as well as the models for the cone surface area is incorporated into integrated software. Utilizing the software, we analyze the fluctuating pressure loads around a reentry vehicle under a range of high Mach numbers. The results show that the most critical fluctuating pressure load is induced by the shock/boundary layer interaction in the root area around the control panel. It not only can cause potential structure failure but also has effects on the vehicle's aerodynamic performance and the efficiency of the control panel.