A numerical study to reduce the drag effects in hypersonic flow over the backward facing step

A numerical simulation study of laminar hypersonic cold airflow over the backward-facing step (BFS) is performed at a freestream Knudsen number of 0.00009589 for resolving the flow field. The effects on the wall properties caused by the expansion of the flow and the separation of the boundary layer at the step corner have been investigated. The contributions of pressure and viscosity to the coefficients of lift and drag have been elucidated. It is seen that an increase in step height "nh" from n = 1 to 5 for a freestream flow at Mach 7.6 produces an incremental effect on the C-L/C-D ratio, whose range is between -1 to 1 for the variations in the step height simulated. The current study concludes that BFS yet remains a geometry that contributes to more drag than lift, however that effect can be minimized by increasing the step height during the design process of hypersonic vehicles for the above-mentioned Mach number. Copyright (C) 2022 Elsevier Ltd. All rights reserved.