Active control of flows around a bluff body with yaw angle by inducing longitudinal vortices using plasma actuators

Abstract

Active control of flow separation on a bluff body model utilizing dielectric barrier discharge plasma actuators (DBD-PAs) was experimentally demonstrated at Re = 28,000. The model consisting of a flat side plate and a quarter cylinder with a radius of 84.5 mm was placed 200 mm downstream from the exit of the blowing-type wind tunnel and fixed at a yaw angle of 10 degrees relative to the main flow. In the conventional spanwise arrangement of exposed electrode utilizing a string-array-type plasma actuator consisting of six Cu wires coated with silicone rubber and exposed electrodes, the control effect significantly decreased as the distance from the separation point increases. Therefore, blowing-type and suction-type vortex generating plasma actuators (VG-PAs) with exposed electrodes arranged in the streamwise direction were prototyped by combining the string- array-type DBD-PAs, and the effects of suppressing flow separation were verified by generating blowing and suction jets. Both blowing-type and suction-type VG-PAs were effective in suppressing flow separation, with the blowing jet reducing the displacement thickness by 64% and the suction one reducing it by 85% compared to the no control case. Strain rate analysis of the Y-Z cross section revealed that the control effect of the suction-type VG-PA can be obtained over a wider range in the spanwise direction than that of the blowing type VG-PA.