Numerical investigations of pressure loss and heat transfer in a 180° bend of a ribbed two-pass internal cooling channel with engine-similar cross-sections

Abstract

Numerical investigations of a two-pass internal cooling channel with engine representative cross-sections related to turbine blade cooling were conducted. The channel consisted of a trapezoidal leading edge pass, a sharp 180° bend, and a nearly rectangular outlet pass. The numerical predictions were validated against experimental results in terms of pressure distributions, total pressure losses, and local heat transfer coefficient distributions. The investigations focused on the influence of rib turbulators and tip-to-web distance on the pressure loss and heat transfer. The channel was equipped with skewed ribs (α = 45°, P/ e = 10, and e/ dh = 0.1) in a parallel and a staggered configuration. The dimensionless tip-to-web distance Wel/ dS was varied from 0.6 to 2.0. The investigated Reynolds number was 50 000. The computational study was performed by solving the Reynolds-averaged Navier—Stokes equations with the commercial finite-volume-solver FLUENT and three turbulence models: the realizable k—ε turbulence model with a two-layer wall treatment, the k—ω—SST model, and the v2– f model. The computations were performed on hybrid, unstructured grids created with the semi-automatic grid generator CENTAUR. The predictions using the k—ω—SST model were in overall agreement with the experimental results, showing an increasing pressure loss with a decreasing tip-to-web distance while the heat transfer was increased to a smaller extent.