Effect of blowing ratio on the relaminarization phenomenon over convex curved wall

Relaminarization is a reverse transition from turbulent state to laminar or laminar-like state as the turbulent boundary layer is accelerated, which cause the boundary layer easy to separate under the adverse pressure gradient. To investigate the mechanism of relaminarization flow control with air injection, large eddy simulations were performed for a turbulent flow over a convex curved wall at Mach number 3.0 under different blowing ratios. The results show that the acceleration has markedly reduced the turbulent characteristics including the number of large-scale turbulent structures and the turbulence kinetic energy values in the boundary layer for the baseline case. As the air injection is excited, the relaminarization is effectively suppressed. Meanwhile, the simulation reveals that the blowing ratio plays an important role in controlling the turbulence. The air injection with higher blowing ratio is more effective in suppressing the relaminarization under the condition that the jet-to-cross flow momentum flux ratio and static pressure of injected air are kept unchanged.