Numerical simulation of forced boundary layer transition on hypersonic vehicle forebody

Forced boundary layer transition is a key technology to ensure scramjet normal start, and the k-ω-γ transition model is an effective way to predict hypersonic boundary layer transition. To study the prediction performance of the k-ω-γ transition model on forced boundary layer transition and the effects of different trips on boundary layer transition, a wall temperature effect modification is conducted on the original k-ω-γ transition model, and the modified k-ω-γ transition model is employed to investigate the forced boundary layer transition ona hypersonic vehicle forebody. The transition onsets of forebodies with no trip, with diamond trips and with ramp trips under Mach 6 and 7 are studied by numerical simulation, and the results are compared with those from the experiment. It is found that the modified k-ω-γ transition model can well predict forced boundary layer transition, and the transition onset locations of numerical simulation are consistent with experiment results. Both diamond trips and ramp trips can obviously promote boundary layer transition forward to reduce flow separation and lateral flow spillage. Disturbances caused by diamond trips are stronger than those by ramp trips, and the transition length is shorter than that of ramp trips as well. However, ramp trips show a better performance on controlling boundary layer flow separation and reducing lateral flow spillage compared with diamond trips.