Effect of Coriolis and Centrifugal Forces on Turbulence and Transport at High Rotation and Buoyancy Numbers in Internal Cooling U-Channels with Smooth Walls

Abstract

Numerical simulation of fluid flow and heat transfer for high rotation and density ratio flow in internal cooling channels with smooth walls of turbine blades is the main focus of this study. The flow in theses channels is affected by Rotation, buoyancy, bends and boundary conditions. On the basis of comparison between two-equation (k-e and k-ω) and RSM turbulence models, it is concluded that the twoequation turbulence models cannot predict heat transfer correctly, while RSM showed improved prediction. Thus RSM model with wall functions for near wall treatment was validated against available experimental data (which are primarily at low rotation and buoyancy numbers). The model was then used for cases with high rotation numbers (as much as 1.29) and high-density ratios (up to 0.4). Particular attention was given to how Reynolds stresses, turbulence intensity and transport are affected by coriolis and buoyancy/centrifugal forces caused by high levels of rotation and density ratio. The results obtained are explained in view of physical interpretation of coriolis and centrifugal forces.