Flow Separation Induced by Periodic Aerodynamic Interference
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
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Analysis of experimental surface pressure distributions on an NACA 0012 airfoil has revealed four flow states attached, separated, borderline, and dynamically separated. The important parameters that determine the flow state are Reynolds number, reduced frequency, airfoil angle of attack, and surface condition at the leading edge. Testing was done at Re700,000, .5k6.4, and 0alpha18 degrees. For this flow the dynamically separated state takes the form of an alternation between attached and separated flow. It has a period that ranges from 1 to 30 times that of the unsteady perturbation. In the separated state a convected surface pressure disturbance was identified, and found to propagate downstream from a location near the leading edge at a phase speed of 13 to 12 that of the freestream velocity.
- Fluid Mechanics