Drag Reduction Effect by a Self-Adjustable Splitter Plate on the Flow over a Circular Cylinder

원형실린더 후류내의 가동형 와류분할판에 의한 항력 감소효과

The drag reduction effect of a freely-rotatable splitter plate was experimentally investigated in the 2-D wake behind a circular cylinder. By arranging the splitter plate to be aparted with a certain gap from the cylinder, the splitter plate was able to be aligned itself automatically to the flow direction in the tested range of 6.2$\times$$10^3$$\times$$10^4$. As a result, it was proven that the self-adjustable splitter plate always reduced effectively the drag imposed on the body against any arbitrary flow directions. In a specific range of Reynolds numbers, the drag reduction effect was dependent not only on the length of the splitter plate but also on the gap distance between the plate and the trailing edge of the body. For a splitter plate with a specific length, there existed a unique optimum range of gap distance to obtain successfully the drag reduction effect, however, the optimum range of gap distance was dependent on Reynolds number.

본 연구에서는 가동형 분할판을 실린더 후단부로 부터 일정간격 이격시켜 설 치하여, 실린더 바로 후방의 압력에 의한 불안정한 모멘트가 분할판에 직접 작용하지 않도록 하되 와동의 상호 작용은 계속 억제할 수 있도록 설계된 가동형 분할판을 이용 하여 이의 항력 저감효과를 풍동실험을 통하여 조사하였다.