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International Journal of Rotating Machinery
Volume 2012, Article ID 509209, 14 pages
http://dx.doi.org/10.1155/2012/509209
Research Article

Effect of the Radial Pressure Gradient on the Secondary Flow Generated in an Annular Turbine Cascade

Mechanical Engineering Department, Benha Faculty of Engineering, Benha University, Benha 13512, Egypt

Received 17 October 2011; Revised 19 March 2012; Accepted 20 March 2012

Academic Editor: J.-C. Han

Copyright © 2012 Hesham M. El-Batsh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper introduces an investigation of the effect of radial pressure gradient on the secondary flow generated in turbine cascades. Laboratory measurements were performed using an annular sector cascade which allowed the investigation using relatively small number of blades. The flow was measured upstream and downstream of the cascade using a calibrated five-hole pressure probe. The three-dimensional Reynolds Averaged Navier Stokes equations were solved to understand flow physics. Turbulence was modeled using eddy-viscosity assumption and the two-equation Shear Stress Transport (SST) k-ω model. The results obtained through this study showed that the secondary flow is significantly affected by the pressure gradient along blade span. The experimental measurements and the numerical calculations predicted passage vortex near blade hub which had larger and stronger values than that predicted near blade tip. The loss distribution revealed that secondary flow loss was concentrated near blade hub. It is recommended that attempts of reducing secondary flow in annular cascade should put emphasis on the passage vortex near the hub.