Experimental investigation of separation bubble control behind a backward-facing step with curved edge using plasma actuators

Tite: Experimental investigation of separation bubble control behind a backward-facing step with curved edge using plasma actuators (DOI)
​​​​​​​Authors:  Hossein Ghaderian, Sohrab Gholamhosein Pouryoussefi.
Journal:  Acta Mechanica
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Abstract: The backward-facing step (BFS) is an appropriate model for studying flow separation. In this study, controlling separation bubbles behind a curved edge BFS with plasma actuators was investigated experimentally in Reynolds numbers ranging from 17 × 103 to 51 × 103 (depending on step height). Smoke flow visualization experiments were conducted to analyze the flow pattern around a BFS in the presence of a plasma actuator. Pressure distributions were measured under a variety of situations and analyzed. Seven curved edges were created, with a radius of curvature ranging from 0 (a sharp edge) to 50 mm. The results reveal that the length of the separation bubble decreases as the radius of curvature increases. Another series of experiments were carried out for bigger radius of curvature, studying the location of the placed plasma. The location varies when the angle with respect to the center of curvature changes. Plasma actuators were mounted on the curvature at two different angles (0 and 20 degrees). Both plasma actuators were utilized simultaneously at angles of 0 and 20 degrees. The best results were obtained by putting two plasma actuators on curvature at the same moment, which results in lowering reattachment length. The separation bubble's length was also lowered by using a plasma actuator at a 20-degree angle according to the center of the radius of curvature.