Abstract:

The transition mechanism of a hypersonic boundary layer in the conditions of high Mach number and high Reynolds number is investigated, and the evolution of instable structures is analyzed.The numerical method is large eddy simulation (LES).The spatial transition coherent structure of a hypersonic blunt-wedge boundary layer at a free-stream Mach number of Ma_∞=6.0 based on freestream velocity and a Reynolds number of Re=2.0×10⁶/inch is studied with a hybrid method of a fifth order upwind compact difference and a eighth-order symmetric compact difference for the three-dimensional compressible Favre-filtered Navier-Stokes equations.The compact storage third-order explicit Runge-Kutta method is applied for time-integration.The sub-grid scales are formulated according to the modified Smagorinsky eddy-viscosity model.Based on the linear stability theory,a particular perturbation of blowing and suction is int roduced close to wall as unstable disturbances on the inflow boundary.The obtained flow process is divided into three stages:the linear and weakly no nlinear growth of disturbance,transition,and full turbulence.The result presents that LES can simulate hypersonic blunt-wedget ransition well.

Key words: transition,  , turbulence,  , compressible , boundary , layer,  , large , eddy , simulation