Abstract

Numerical simulation and experimental validation of a hypersonic flat plate and isothermal turning wall flow were conducted in the current study. The investigation was based on three kinds of grids (Grid1, Grid2 and Grid3) with laminar flow and three types of turbulence models (BL, SA and SST). Under the same initiation and different turbulence models, the convergence process of the friction drag coefficient C_P and the Stanton number St of a hypersonic flat plate flow revealed four results. First, the flow turbulence effect in the BL model simulation was responsive to C_P and St. Second, the SA and SST model simulations both reflected the development process of flow turbulence. Third, the flow turbulence effect in the SST model simulation did not gradually emerge until the laminar flow simulation was sufficient. Moreover, the SA model simulation did not exist on such obvious hysteresis. Fourth, by comparing C_P and St of a hypersonic flat-plate laminar simulation under the three grids, the errors of the calculation results of Grid2 and Grid3 were small. In contrast, the error on Grid1 was large. By comparing C_P and St of the BL model for the three grids, we found that the result of Grid3 was slightly better than the result of Grid2. The deviation between them basically remained within 10%. However, the result of Grid1 had a large deviation with oscillation. C_P and St of the SA model for the three grids were then compared. A large difference was found only on the transition zone location between the result of Grid2 and Grid3. Nevertheless, the error and calculation of reference between them was maintained within 10%. Grid1 not only had a large deviation, but also had certain oscillation on the laminar flow area. Finally, C_P and St of the SST model for the three grids were compared. There was a large difference only on the transition zone location between the result of Grid2 and Grid3, but the error between them was maintained within 10%. Grid1 had a large deviation. The hypersonic flat-plate laminar flow was also compared with C_P and St calculated from the three turbulence models for the three grids. Evidently, the grids near the wall must be encrypted to an appropriate extent to simulate more accurately the boundary laminar flow as well as obtain proper surface friction and heat flow. The calculation in the present study showed that the Reynolds number in the first layer of the grid was more reasonable when it was about 20. The simulation result for the hypersonic isothermal two-dimensional turning wall flow showed that the calculation and experiment results from the different turbulence model were consistent. There was little difference between the location of the simulated heat flow peak and the position given by experiment. However, the peak, the curve trend after the peak and the experimental result widely differed. The curve and experimental results for pressure distribution greatly varied because of the existence of an isolated area in the calculation of the laminar flow. The calculation and experimental results from different turbulence models were close. The curve trend, the peak and the experimental result basically matched.

Keywords:

Grid, hypersonic, BL, SA, SST, turbulence model,

References

Competing interests

The authors have no competing interests.

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