NUMERICAL STUDY OF UNSTEADY SUPERSONIC COMPRESSION RAMP FLOWS

Through numerical study using a moving grid system, inviscid supersonic flow past a moving compression ramp was investigated. The study revealed that the unsteady flow of the moving ramp could be considered steady or quasi-steady when Ω¯ was of order 0.01 or smaller. When Ω¯ was 0.1, the flow exhibited distinct unsteady behavior. The shock wave formed during the ramp motion was curved rather than straight. The surface pressure during the ramp motion was higher than the steady state value of the corresponding steady ramp. After the ramp motion ceased, it took a considerable time for the pressure to relax to the steady state value. When Ω¯ = 1.0, the shock wave development was confined in the narrow region close to the moving surface. This shock wave then gradually moved away from the wall after the ramp stop and was finally developed to that of the steady state. When the ramp moved cyclically from −20 to 20 deg, hysteretic behavior of the flow was noticed. © 1994 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.