Effect of combined impingement cooling and film cooling on hybrid cooling effectiveness

The present study concentrates on the computational investigation of a new cooling configuration of a double-layer cavity in the middle section of modern turbine blade. A three-dimensional Navier-Stokes code with standard k-ε turbulence model as well as with wall functions was used to compute the flow and heat transfer characteristics for a combined impingement and film cooling configuration. The blowing ratios are from 0.6 to 2.0, and the Reynolds number based on the inlet velocity of the cooling air and hole diameter varied from 2000 to 5000. Additionally, the effect of the arrangement of both impingement hole and film hole on hybrid cooling effectiveness was discussed. Numerical results reveal that the maximum of hybrid cooling effectiveness is localized at a distance of 3.3 d and 9d from the beginning of the cavity leading edge to film cooling hole and impingement hole, respectively. For the present computational domain, a double peak distribution of the Nusselt number on impingement target was demonstrated, and the stagnant point is localized at the valley between these two peaks.