Reattachment studies of an oscillating airfoil dynamic stall flow fieldThe reattaching flow over an oscillating airfoil executing large amplitude sinusoidal motion around a mean angle of attack of 10 degrees has been studied using the techniques of stroboscopic schlieren, two component laser Doppler velocimetry and point diffraction interferometry, for a free stream Mach number of 0.3 and a reduced frequency of 0.05. The results show that the dynamically stalled flow reattaches in a process that begins when the airfoil is very close to the static stall angle on its downward stroke and progresses over the airfoil through a large range of angles of attack as the airfoil decreases to about 6 degrees. The airfoil suction peak shows a dramatic rise as the static stall angle is approached and the velocity profiles develop such that the flow near the surface is accelerated. The process completes through the disappearance of a separation bubble that forms over the airfoil.
Document ID
19910069250
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Ahmed, S. (MCAT Institute San Jose, CA, United States)
Chandrasekhara, M. S. (NASA Ames Research Center Moffett Field; U.S. Navy-NASA, Joint Institute of Aeronautics; U.S. Naval Postgraduate School, Monte, United States)