Flow and heat transfer characteristics of a novel jet impingement cooling with multi-layer drainage channels at blade leading edge

Advanced and efficient cooling strategies are critical for safety operation and reasonable durability of turbine blades. Impingement drainage cooling, a novel jet impingement cooling with multi-layer drainage channels, is presented in this paper. Three different cooling configurations utilizing the novel jet impingement scheme are numerically investigated and comprehensively compared with conventional jet impingement cooling under turbine operating conditions. The results indicate that the impingement drainage cooling requires lower supply pressure of cooling air and produces less flow loss. Each jet of impingement drainage cooling generates a pair of counter-rotating vortices in the transverse direction, differing from the longitudinal vortices typically observed in the conventional cooling. Drainage channels and modular cooling construction effectively prevent crossflow and jet deflection, improving heat transfer and reducing leading-edge temperatures by at least 20 K with less cooling air, compared to the conventional impingement cooling scheme. Furthermore, the drainage channels combined with double-wall blade frame allows the reutilization of the cooling air from the leading edge, thereby enhancing coolant utilization. The impingement drainage cooling provides favorable information for turbine blade cooling design in gas turbines.