Computational study of supersonic flow past non-stationary obstructions part-I-moving ramp

Abstract

For an upward moving ramp, compression waves of progressively increasing strengths emanate from the ramp surface and eventually coalesce into an oblique shock. A lag in wall pressure build up relative to fixed ramp values is observed which depends on ramp angle and angular velocity in a direct fashion. For an oscillating ramp, wall pressure response to varying ramp angles displays a hysteretic behaviour. Compressive/expansive effects generated during the ramp's upward/downward motions persist after the ramp changes its direction. Lags are observed during both wall pressure build up and relaxation which exhibit a similar dependence to ramp angle and angular velocity as in case I. The effect of ramp motion on boundary layer (thinning/thickening during upward/downward motions) is explained on the basis of fluid inertia and is reflected in increasing/decreasing velocity gradients inside the boundary layer. This in turn affects wall skin friction and temperature distributions inside the boundary layer. Copyright © 2015 Inderscience Enterprises Ltd.