Shock wave-Boundary Layer Interactions in Wedge-induced Oblique Detonations

Abstract

ABSTRACT The flow structure and stability of oblique detonation waves (ODWs) affected by shock wave-boundary layer interactions (SBLIs) are investigated based on Reynolds averaging method. ODWs with smooth and abrupt transitions are studied separately. The results show that there are no shock waves behind detonation wave surface for ODWs with smooth transitions, so the flow structures are only affected by the ramp-induced SBLI. Under the circumstances, the compression effects of the focused shock instead of the separation shock is the main cause of the initiation of ODW, which leads to an obvious increase in the initiation length. In ODWs with abrupt transitions, the primary transverse wave is formed and reflects on the wedge surface. Besides the ramp-induced SBLI, post-wave SBLI also occurs. The two kinds of SBLIs are influenced by the thickness of the inflow boundary layer and the activity of the inflow mixture. When the inflow boundary layer is thin and the activity is low, the separation zone is small and the distance between the ramp-induced separation zone and the post-wave separation zone is large, which makes the ramp-induced separation separated from the post-wave subsonic area. The post-wave SBLI makes the shock configuration at the end of the induction zone change from the λ-shaped to the Y-shaped, which weakens the stability of the ODW. When the inflow boundary layer is thick or the activity is high, the separation zone is large and the distance between the two separation areas is large, which makes the ramp-induced separation merge with the post-wave subsonic area and an extended separation is formed which covers the wedge surface. As the flowfield develops, the extended separation becomes larger and larger, leading to further increase of the initiation length. Finally the ODW propagates out of the calculation domain and fails to be stabilized on the wedge surface.