The steady-state aerodynamic characteristics of a new family of blunted leading edges immersed in a high-speed rarefied air flow are examined by using a Direct Simulation Monte Carlo (DSMC) Method. A very detailed description of the flow properties has been presented separately at the vicinity of the nose and adjacent to the afterbody surface of the leading edges by a numerical method that properly accounts for non-equilibrium effects that arise near the leading edges and that are especially important at high Mach number. Comparisons based on geometry are made between these new blunt configurations and round leading edge. Some significant differences between these leading edges are noted on the flowfield structure and on the aerodynamic surface quantities. It is found that the upstream effects have different influence on velocity, density, pressure and temperature along the stagnation streamline ahead of the leading edges. The analysis also shows that, despite the seeming advantages of the new blunt leading edge shapes, round leading edge still provides smaller stagnation point heating. Nevertheless, round leading edge provides larger total drag than the new blunt shapes under the range of condition investigated.

Effects of incomplete surface accommodation in rarefied gas flow have been studied by using the Direct Simulation Monte Carlo (DSMC) method in conjunction with the Cercignani-Lampis-Lord gas surface interaction model. The DSMC calculations examine differences in predictions of aerodynamic forces and heat transfer between full and partial surface accommodation for hypersonic flow past round leading edges at zero incidence. The aerodynamic performance of round leading edges is assessed by using the heat transfer rate, the total drag and the shock wave standoff distance. Twenty-five combinations of nose radius, normal and tangential accommodation coefficients were used in the simulation. For the flow conditions considered, the analysis showed that stagnation point heating, total drag and shock standoff distance are sensitive to changes on either the normal or tangential accommodation coefficient. The results substantiate that it becomes imperative to take surface accommodation into account in order to make accurate predictions of the aerodynamic forces on, and heat transfer rates to, bodies in rarefied hypersonic flow.

Hypersonic flow past truncated wedges at zero incidence in thermal non-equilibrium is investigated for a range of Mach number from 5 to 12. The simulations were performed by using a Direct Simulation Monte Carlo (DSMC) Method. The study focuses the attention of designers of hypersonic configurations on the fundamental parameter of bluntness, which can have an important impact on even initial design. Some significant differences between sharp and blunt leading edges were noted on the heat transfer, pressure and skin friction coefficients as well as on total drag. Interesting features observed in the surface fluxes showed that small leading edge thickness compared to the freestream mean free path still has important effects on high Mach number leading edge flows. The numerical results present reasonable comparison for wall pressure and heat transfer predictions with experiments conducted in a shock tunnel.