Numerical Investigation of an Integrated Impingement and Pin-Fin Cooling Configuration in a Wedge Duct

In the gas turbine blade cooling design, impingement insert and pin-fins arranged as an array in the trailing region are usually used to enhance the heat transfer. To investigate the heat transfer characteristics of the integrated impingement and the pin-fin cooling configuration in wedge channels, the numerical simulations with k-ε turbulence model and scalable wall function algorithm are carried out using a commercial CFD code. To reveal the factors that enhance the heat transfer in the blade internal trailing channel, heat transfer characteristics of pin-fins with impingement slot are compared with that without impingement slot. The effect of the ratio of jet impingement distance to pin-fin diameter on the heat transfer is analyzed. The convergence angle of the channel is studied. The heat transfer characteristics of the integrated impingement and pin-fin cooling configuration in the wedge channels are evaluated. The results reveal that the impinging jet enhances largely the heat transfer in the first two rows. In the studied range of L/D = 0.5∼2.0, the heat transfer of the pin-fins with impingement is about 20%∼25% higher than that without impingement. The averaged Nusselt numbers on the endwall surface, the pin surface, and the overall surfaces respectively in the wedge duct increase linearly with the increase of Reynolds number, decrease gradually with the increase of the impingement distance and increase with the increase of the convergence angle.