Hypersonic Boundary-Layer Transition Forced by Wall Injection: A Numerical Study

The laminar-turbulent transition of a Mach 4.6 flat-plate boundary layer forced by a wall underexpanded jet is investigated using implicit large-eddy simulation based on a fifth-order weighted essentially nonoscillatory scheme. The boundary-layer edge conditions match those of a 1 :3-scale hypersonic vehicle forebody at Mach 6 in the T-313 conventional blowdown wind tunnel of the Institute of Theoretical and Applied Mechanics, Russian Academy of Science at Novosibirsk. The effects of injection pressure and jet pulsation on the structure and the stability of the near-injection flow are investigated. Downstream breakdown to turbulence is analyzed through Q-criterion visualization, mean velocity profiles, and skin friction coefficients. Results show that a low-pressure injection is enough for effective tripping, and that a nonpulsed jet is paradoxically more efficient than a pulsed one.