국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Delay of Turbulent Boundary Layer Detachment by Mechanical Excitation: Application to Rearward-Facing Ramp
저자	Daniel J. McKinzie, Jr.
Keyword	Rearward-facing ramp; Separation; Detachment; Diffuser
URL	http://gltrs.grc.nasa.gov/reports/1996/TP-3541.pdf
보고서번호	NASA TP-3541
발행년도	1996
출처	NASA Glenn Research Center
ABSTRACT	A vane oscillating about a fixed point at the inlet to a two-dimensional 20?rearward-facing ramp proved effective in delaying the detachment of a turbulent boundary layer. Flow-field, surface static pressure, and smoke-wire flow visualization measurements were made. Surface pressure coefficient distributions revealed that two different effects occurred with axial distance along the ramp surface. The surface pressure coefficient varied as a complex function of the vane oscillation frequency and its trailing edge displacement amplitude; that is, it varied as a function of the vane oscillation frequency throughout the entire range of frequencies covered during the test, but it varied over only a limited range of the trailing edge displacement amplitudes covered.The complexity of these findings prompted a detailed investigation, the results of which revealed a combination of phenomena that explain qualitatively how the mechanically generated, periodic, sinusoidal perturbing signal produced by the oscillating vane reacts with the fluid flow to delay the detachment of a turbulent boundary layer experiencing transitory detachment.