Parametric study of a k-ω-γ model in predicting hypersonic boundary-layer flowtransition

Predicting hypersonic boundary layer transition accurately is important to thermal protection and drag reduction of vehicle. However, many factors affect the process of hypersonic boundary layer transition. To study the impact factors of boundary layer transition from the transition model aspect, simulations on boundary layer transition of a 5 ° cone were carried out by using k-ω-γ transition model under different nose bluntness, frees-steam Reynolds numbers (Re_∞) and turbulence intensities (FSTI), and compared with the wind tunnel results. Some conclusions were obtained: k-ω-γ transition model can basically reflect the effects of nose bluntness, Re_∞ and FSTI on hypersonic boundary layer transition, however not well in predicting the heat peak following the transition; from the view of formulation of transition model, reducing the nose bluntness or increasing the Reynolds number can decrease the boundary layer thickness, which leads to the increase of the time scales of both the first mode and the second mode, and then the transition occurs prematurely; the FSTI is larger, the equivalent fluctuation kinetic energy is stronger in the laminar zone of the boundary layer, and boundary layer transition takes place easily.