Investigation of corner separation and suction control in constant area duct

To control shock-wave/boundary-layer interaction with suction, numerical simulations in a constant-area rectangular isolator with asymmetry nozzle are conducted to understand the complex flow phenomena. Results show that three-dimensional effect significantly weakens isolator resistance to backpressure, which indirectly emphasizes enormous role of viscous effect and geometry to the dynamic behavior of shock train or pseudo-shock wave. The large-scale separated flow only locates at the corner of the upper wall. The mechanism analysis indicates that the flow is accelerated more rapidly along the bottom wall, thereby providing more momentum at the nozzle exit. The displacement and momentum thicknesses and their increasing rate on the upper wall are all greater than that of the bottom wall, which means that upper corner flow is subjected easily to separation. The vortex structure of different cross sections in the pseudo-shock region is formed in different ways and the large-scale vortex still exists after the airflow mixing, which contributes to the deceleration and pressurization. Through the control effect analysis of suction slot, the suction slot in spanwise direction on the side wall can shorten effectively the length of shock train, which indicates that removing the low-momentum fluid near the corners can control significantly the shock-wave/boundary-layer interactions. (C) 2017 Elsevier Masson SAS. All rights reserved.