The Effect of Varying Freestream Velocity on Airfoil Dynamic Stall Characteristics
Authors: Pierce, G. Alvin; Kunz, Donald L.; Malone, John B.
Source: Journal of the American Helicopter Society, Volume 23, Number 2, 1 April 1978 , pp. 27-33(7)
Publisher: AHS International
Abstract:A low speed wing tunnel equipped with an axial gust generator to simulate the aerodynamic environment of a helicopter rotor was used to study the dynamic stall of a pitching blade. The objective of this investigation was to find out to what extent harmonic velocity perturbations in the freestream affect dynamic stall. The study involved making measurements of the aerodynamic moment on a two‐dimensional, pitching blade model in both constant and pulsating airstreams. Using an operational analog computer to perform on‐line data reduction, plots of moment versus angle of attack and work done by the moment were obtained. The data taken in the varying freestream were then compared to constant freestream data, and to the results of two analytical methods. These comparisons showed that the velocity perturbations had a significant effect on the pitching moment which could not be consistently predicted by the analytical methods, but had no drastic effect on the blade stability.
Document Type: Research Article
Affiliations: Georgia Institute of Technology, Atlanta, Georgia
Publication date: April 1, 1978
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