Transition model and transition criteria for hypersonic boundarylayer flow

This paper presents some modifications to the original k-ω-γ transition model and “laminar+transition criteria” model. The crossflow instability time scale and the crossflow criterion have been developed and added to the original k-ω-γ transition model and “laminar+transition criteria” model, respectively. With pretreatment of computational grid the boundary layer edge and crossflow velocity can be obtained using parallel methodology. Comparison of the two methods for hypersonic boundary layer transition prediction has been accomplished via sharp cone at different Reynolds numbers and HIFiRE-5 shape. Results have proven that both k-ω-γ transition model and “laminar+transition criteria” model can predict correct transition onsets and lengths at different Reynolds numbers, but fail to predict the heat overshoot observed in experimental results. The heat transfer in fully turbulent region predicted by “laminar+transition criteria” model is larger than k-ω-γ transition model and the reason for this has been analyzed. For HIFiRE-5 in which the boundary layer transition is dominated by streamwise instabilities and crossflow instabilities, the k-ω-γ transition model and “laminar+transition criteria” model with modifications show a better prediction for the crossflow induced transition than the models without modifications. However, for the transition dominated by the velocity profile inflection point, using “laminar+transition criteria” model which is associated with boundary layer thickness is inappropriate and can predict transition onset prematurely, while the k-ω-γ transition model presents good agreement with the test.