Boundary layer separation control on an inclined plate using Jet and Vortex Actuator

In this numerical study a Jet and Vortex Actuator (JaVA) system is implemented on an inclined p late (with an inclination angle 60) to control the laminar boundary layer separation. JaVA is an active flow control device similar to the synthetic jets that transports momentum into the boundary layer and interacts with the boundary layer velocity profiles. The JaVA used in this study is a two-dimensional rectangular cavity with an actuating plate mounted on the opening which is placed asymmetrically. The plate moves up and down in vertical direction with a specified frequency. As the actuating plate is mounted asymmetrically on the cavityopening, there are one narrow (w_n) and one wide gap (w_w) between the plate and the cavity. First JaVA in a cross-flow on an inclined p late (with inclination angle 6°) is modeled using a computational domain including a moving zone to mimic the vertical motion of the actuating plate. As plate moves up and down like a p iston, JaVA-induced vortices emanate from the wide gap and are injected into the oncoming boundary layer. The calculations are carried out by a commercial finitevolume- based unsteady, laminar, incompressible Navier-Stokes solver. Time-averaged flow fields are calculated to extract boundary layer profiles from various downstream stations. For different oscillation frequencies (f = 1, 2, 3 and 4 Hz) time averaged boundary layers are compared to the non-actuated case (f = 0). The variations of the important boundary layer characteristics (displacement thickness, momentum thickness, shape factor) as well as friction coefficient are also investigated. It is observed that with increasing plate frequency or jet-Reynolds number (Re_J= 4abf/?), JaVA-induced vortices interact with the cross-flow and modify the boundary layer characteristics. This has been shown in the time-averaged velocity profiles with a fuller shape causing larger displacement thicknesses and in association with them the shape factors drop and the friction coefficients increase. The proposed control method based on alternating suction and blowing with an oscillating plate is effective in delaying or preventing the flow separation downstream o f an inclined plate.