Numerical Investigation of Heat Transfer in Turbine Cascades With Separated Flows

Abstract

Modern design of turbine blades usually requires highly loaded, very thin profiles in order to save weight and cost. If local leading edge incidence is kept close to zero, then flow separation might occur on the pressure side. Although it is known that flow separation, flow reattachment, and the associated zones of recirculation have a major impact on the heat transfer to the wall, the turbomachinery community needs an understanding of the heat transfer mechanisms in separated flows as well as models and correlations to predict them. The aim of the present investigation is a detailed study by means of an in-house CFD code, MU2S2T, of the heat transfer mechanisms in separated flows, in particular in separation and reattachment point regions. Furthermore, an attempt is made to identify a limited number of parameters (i.e., Re, M, inlet flow angle, etc.) whose influence on the heat flux would be critical. The identification of these parameters would be the starting point to develop special correlations to estimate the heat transfer in separated flow regions.

Heat Transfer in Separated Flows on the Pressure Side of Turbine Blades

“…Regarding experimental investigations, Rivir et al [10] have measured the flat plate heat transfer in a region of turbulent separation, and Bellows and Mayle [11] have measured the heat transfer on a blunt body leading edge separation bubble both for cases of high Reynolds number. More recently, De la Calzada and Alonso [12] performed a numerical investigation of large flow separation region at the pressure side of a turbine profile but not comparison with experimental results was included. Lutum and Cottier [13] presented a similar investigation, but results indicated that simulations were not able to reproduce experimental heat transfer results at the pressure side separation region especially for low turbulence levels.…”