Response of hot element wall shear stress gages in laminar oscillating flowsAn experimental investigation of the time-dependent response of hot element wall shear stress gages in unsteady periodic air flows is reported. The study has focused on wall shear stress in laminar oscillating flows produced on a flat plate by a free stream velocity composed of a mean component and a superposed sinusoidal variation. Two types of hot element gages, platinum film and flush wire, were tested for values of reduced frequency ranging from 0.14 to 2.36. Values of the phase angle of the wall shear stress variation relative to the free stream velocity, as indicated by the hot element gages, are compared with numerical prediction. The comparisons show that the gages indicate a wall shear stress variation that lags the true variation, and that the gages will also not indicate the correct wall shear stress variation in periodic turbulent flows.
Document ID
19860053723
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Cook, W. J. (Iowa State University of Science and Technology, Ames, United States)
Murphy, J. D. (NASA Ames Research Center Moffett Field, CA, United States)
Giddings, T. A. (Iowa State Univ. of Science and Technology Ames, IA, United States)