국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Visualization of Separated Flows over the Circular Cylinder at High Reynolds Numbers
저자	Mamoru Sato, Hiroshi Kanda, Hisashi Suenaga, Norikazu Sudani, Masashi Shigemi
Keyword	flow visualization; circular-cylinder; three-dimensional separation; boundary layer; two-dimensional wind tunnel
URL	http://send.nal.go.jp/send/jpn/dlpdf.php3/naltr0001378.pdf?id=NALTR0001378
보고서번호	NAL TR-1378
발행년도	1999.01
출처	NAL (National Aerospace Laboratory of Japan)
ABSTRACT	Flow visualization tests have been conducted in the NAL Two-Dimensional Transonic Wind Tunnel to investigate the boundary layer separation over circular-cylinder models at Reynolds number range of 5×105 to 30×105 and a Mach number of around 0.5. The laminar separation bubbles are observed on the surface around the critical Reynolds number and the cell-like structures are seen along the span. As Reynolds number increases, the laminar bubbles disappear and the flow field becomes more complicated. The ratio of the average cell length to the cylinder diameter is about 0.3 to 1.3 at Reynolds number of 20×105. Results of the visualization tests show that the separated flow is three-dimensional. We have established the liquid crystal technique to visualize boundary layer flows in the blow down wind tunnel.