In this numerical work, we investigate supersonic compressible laminar flow past a moving compression ramp. The ramp moves from 0 to 10 degrees wedge angle at constant angular speed. When the ramp moves to the final wedge angle, the ramp stops suddenly. Three cases of different angular speed have been computed to examine the unsteady behavior. The reduced angular velocity defined by ΩL/U for these three cases is 0.01, 0.1 and 1.0.
To solve the two dimensional compressible Navier-Stokes equations, we employ a finite volume method with 2nd order upwind-TVD scheme for spatial derivatives, and Runge-Kutta explicit method for time integration. To simulate moving boundary problems, the transformation metrics should be treated carefully. In the present work, Jacobians have been updated by solving a geometric conservation law (GCL) along with the flow conservation laws. Meshes on which analytic grid velocities can be computed have been generated algebraically at each time step.
During the ramp motion, the flow exhibits distinct unsteady behavior. The wall pressure increases as the linear velocity of ramp motion increases. The separation bubble around the corner of the moving wedge evolves gradually and hence is small in size when compared to the size of the corresponding steady state wedge. After the ramp stops, the size of the separation bubble continues to grow until it finally reaches its steady state configuration in a considerably long time period.
