返回Google圖書搜尋

Experimental Investigations Into Shark Skin Inspired Active Flow Control Mechanisms

出版	University of Alabama Libraries, 2022
URL	http://books.google.com.hk/books?id=4J9NzwEACAAJ&hl=&source=gbs_api

註釋A method for reducing flow separation with actively actuated flaps inspired by bristlingshark scales was studied experimentally using digital particle image velocimetry (DPIV). The flaps in this study had a rectangular shape and were designed with a protrusion heightin the bottom 10% of the boundary layer height, which is similar to that of the flexiblescales found on the mako shark. The flaps were embedded into a flat plate, actuated inunison with frequencies from 0.48 Hz to 5.13 Hz within a water tunnel in a separating turbulent boundary layer flow. These tests were then compared to a corresponding smoothplate case. In the first set of tests, a zero pressure gradient case, it was found that the actuation of the flaps increased the overall momentum in the boundary layer near the wall, when compared to the flat plate case. This momentum increase helps support the hypothesis that the flexible scales of the mako shark help to energize the boundary layer whenself-actuated by the flow. In the second set of tests the model was placed in a separatedregion induced by a rotating cylinder to impose the presence of an adverse pressure gradient. The cases with the actuating flaps showed a reduction in the size of the separatedregion compared to the smooth wall case. These results suggest that the bristling actionof the scales induce mixing within the turbulent boundary layer and is thus an importantcomponent of the mechanism by which flexible shark scales control flow separation.