Unsteady wall pressure characteristics of a 90 degree elbow in high Reynolds numbers

Iwamoto, Yukiharu*; Yamano, Hidemasa   

Wall pressure measurements were made for a 90 degree elbow of which the axis curvature coincided with its inner diameter (125 mm). Reynolds numbers examined were 3.2 10 and 5.0 10. Results showed that distributions of fluctuating normalized pressures obtained here and the result made by Shiraishi et al. for the Reynolds number of 3.25 10 coincided one another within 0.02 of the dynamic pressure. The peak spectrum with the Strouhal number of 0.5 could be found in the inner region downstream of the elbow. They correspond to the vortex shedding from the boundary layer developed in the inner and aft part of the elbow. The peak intensity having the Strouhal number of 0.5 quantitatively coincided with the data obtained in the experimental setup that Shiraishi et al. used, suggesting that the law of dynamical similarity could be applied with regard to this oscillation.