Computational Analysis of Rarefied Hypersonic Flow over a Forward-Facing Step

摘要

The present work performs a computational study on rarefied hypersonic flow past a forward-facing step at zero-degree angle of attack in chemical equilibrium and thermal non-equilibrium. Effects on the aerodynamic surface quantities due to changes on the frontal-face height of the step have been investigated by employing the Direct Simulation Monte Carlo (DSMC) method. The work focuses the attention of designers of hypersonic configurations on the fundamental parameter of surface discontinuity, which can have an important impact on even initial design. The results presented highlight the behavior of the heat transfer, pressure, and skin friction coefficients to changes on the frontal-face height. The analysis showed that hypersonic flow past a forward-facing step is characterized by a strong compression ahead of the frontal face, which influences the aerodynamics surface properties upstream the frontal face. Locally high heating and pressure loads were observed on three locations along the surface, i.e., on the lower surface, on the frontal face and on the upper surface. Results showed that both loads rely on the frontal-face height. The peak values for the heat transfer coefficient on the frontal face surface were at least one order of magnitude larger than the maximum value observed for a smooth surface, i.e., a flat plate without a step.