NUMERICAL STUDIES OF THREE-DIMENSIONAL INSTABILITIES IN NEAR-WALL FLOWOVER A RAMP AT FREE-STREAM MACH NUMBER OF 5.4

摘要

Propagation of three-dimensional (3D) disturbances through the 5.5? compression-ramp flow at the free-stream Mach number 5.373 is simulated numerically. The disturbances are generated by a periodic suction–blowing actuator placed on the wall. 3D Navier–Stokes equations are solved using the in-house parallel solver “HSFlow” on a fine grid. It is shown that the selected forcing excites unstable disturbances relevant to the first and/or second mode instability depending on the actuator frequency. The instabilities evolving through the separation region exhibit nontrivial behavior, which is not captured by 2D simulations. The skin friction coefficient distributions show the presence of the transitional stage where a “young” turbulent wedge is formed.