Interferometric Investigations of Compressible Dynamic Stall Over a Transiently Pitching Airfoil
Abstract
The compressible dynamic stall flowfield over a NACA 0012 airfoil transiently pitching from 0 to 60 deg at
a constant rate under compressible flow conditions has been studied using real-time interferometry. A quantitative
description of the overall flowfield, including the finer details of dynamic stall vortex formation, growth,
and the concomitant changes in the airfoil pressure distribution, has been provided by analyzing the interferograms.
For Mach numbers above 0.4, small multiple shocks appear near the leading edge and are present
through the initial stages of dynamic stall. Dynamic stall was found to occur coincidentally with the bursting of
the separation bubble over the airfoil. Compressibility was found to confine the dynamic stall vortical structure
closer to the airfoil surface. The measurements show that the peak suction pressure coefficient drops with
increasing freestream Mach number, and also it lags the steady flow values at any given angle of attack. As the
dynamic stall vortex is shed, an anti-clockwise vortex is induced near the trailing edge, which actively interacts
with the post-stall flow.
Description
(AIAA Paper 93-0211), AIAA Journal, Vol. 32, No. 3, Mar. 1994, pp. 586-593.
The article of record as published may be found at http://dx.doi.org/10.2514/3.12025
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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