Unsteady Pressure Distributions on Airfoils in Cascade.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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The results of a study of unsteady pressure distributions in a two-dimensional cascade of blades caused by spatial inflow velocity variations are presented. An existing incompressible, inviscid theory which employs a simplified vortex model in conjunction with the assumptions of thin airfoil theory has been used by Henderson and Bruce to derive expressions for the unsteady response, which includes the cascade unsteady lift and pitching moment. An alternative way to obtain these unsteady response parameters is to establish the expression for the unsteady pressure distribution. The unsteady lift and pitching moment are calculated by direct numerical integration over the unsteady pressure difference across the airfoil chord. Comparison of the computed theoretical results using these two approaches shows satisfactory agreement except when the wavelength of the velocity variations approaches the cascade blade spacing. Good agreement is also observed between the existing measured and predicted data. The effects of design parameters of a cascade, such as space-chord ratio, maximum blade camber, and mean incidence angle, on the unsteady response are presented and discussed. Author
- Statistics and Probability
- Fluid Mechanics