Precise estimation of aerodynamic heat around the body of space vehicles while reentry is becoming important for the development of a re-usable space transportation system or a reentry capsule. One of the most important factors is the surface catalysis on the TPS material. In this paper, a new model describing heterogeneous catalysis on the surface of SiO₂-based materials in nonequilibrium flow is summarized. CFD results with this model are compared with some real flight trajectories of reentry vehicles such as OREX. Some examples of the comparison between the experimental results obtained in the ground testing facilities such as an arc-heated wind tunnel and CFD results to validate the essential characteristics indicated in the catalytic model are also shown.

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A series of experiments have been carried out to investigate influence of free-stream turbulence and acoustic noise on laminar-to-turbulent transition in 2-D wing flow. The quantitative evaluation of the influence on the total growth rate N between neutral point and transition point is required for the transition prediction based on the e^N method. Details of natural transition on an identical model were examined in five different wind tunnels. Earlier transition is observed in the wind tunnels with larger acoustic noise and/or larger residual free-stream turbulence. Separate evaluations of free-stream turbulence and sound pressure level lead to an empirical relation between the residual turbulence Tu, the sound pressure level SPL and the total growth rate N as N=-1.32×ln (Tu) -0.003×SPL+6.57 for NACA0015 wing.

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If liquid drop collides with a thin fluid layer, crown-like structure (milk crown) will be formed. In such phenomenon, surface tension is dominant, and a time scale is very short. To catch a continuous image of such phenomena, expensive equipment, such as a high-speed camera, would be required. Therefore, systematic researches which change parameters, such as collision speed of liquid, were not done. Then, we considered how to record with a cheap commercial digital video camera, conducted the systematic experiment by this method, and analyzed the obtained picture. Consequently, we found that the diameter of a crown was proportional to the 1/4th power of the lapsed time after liquid drop collides. That of the trace after a crown disappears was proportional to the 1/2nd power of the lapsed time. The domain where the diameter of a crown is proportional to the 1/2nd power of lapsed time has only been found in the trace after a crown disappeared. We think that the crown turns into the capillary wave during its collapse. We found that the time that the crown grows up is longer than the crown falls down. Considering a simplified model concerning of mass change and surface tension of the crown upper part, we could reproduce the asymmetry.

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