Separating boundary layer response to an unsteady turbulent environment
Gwilliam, David J., Jr.
Howard, Richard M.
Netzer, David W.
MetadataShow full item record
An experimental investigation of the separating boundary layer of a wing subjected to periodic turbulent disturbances was conducted. Turbulence pulses were generated by a non-thrusting spinning rod placed upstream of the test airfoil at the reduced frequencies of .09 and .47. Time-varying velocity measurements were made at various heights above the 70% chord location at 12 degrees angle of attack (nearly separated flow) and 22 degrees angle of attack (fully separated flow). Split-film anemometry was used to determine flow speed and direction. The flow responses were compared to the quasi-steady state of undisturbed separated flow. Variation of reduced frequency had a dramatic influence on the effects which the periodic disturbance had on the flow response. At a reduced frequency of .47 the periodic disturbance had no noticeable influence. Imposition of periodic disturbance of the same reduced frequency on attached flow near separation (12 degrees angle of attack) once again caused no apparent destabilizing effects. The lack of sensitivity of the separated boundary layer to the pulses generated at the higher reduced frequency of .47 apparently resulted from its inability to resolve turbulent pulses from one another. Imposition at 22 degrees angle of attack of a pulse at the reduced frequency of .09, however, first stabilized the flow, then greatly intensified the original separation before allowing the flow to return to its undisturbed separated state.
Approved for public release; distribution is unlimited
Showing items related by title, author, creator and subject.
An inviscid-viscous interaction approach to the calculation of dynamic stall initiation on airfoils Cebeci, T.; Platzer, M.F.; Jang, H.M.; Chen, H.H. (1993-10-01);An interactive boundary-layer method is described for computing unsteady incompressible flow over airfoils, including the initiation of dynamic stall. The inviscid unsteady panel method developed by Platzer and Teng is ...
Yue, Jiannwoei (Monterey, California. Naval Postgraduate School, 1996-09);Flapping airfoils generate thrust-producing jet-like wakes. It therefore is the objective of this investigation to explore whether this feature can be used for effective flow control. To this end, the flow characteristics ...
Yue, Jiannwoei (Monterey, California. Naval Postgraduate School, 1996-09);Flapping airfoils generate thrust-producing jet-like wakes. It therefore is the objective of this investigation to explore whether this feature can be used for effective flow control. To this end, the flow ...