A novel multi-jet impingement drainage cooling: unsteady dynamics and heat transfer mechanisms using large eddy simulation

This study proposes a novel impingement drainage cooling (IDC) configuration with multiple jets for gas turbine blades. The IDC cell integrates baffles and drainage channels, enabling isolated jet impingement and efficient removal of spent coolant. Three jet configurations are analyzed using large eddy simulations to explore unsteady flow and heat transfer mechanisms with jet interaction. The transient behavior and statistical results are first examined. The investigation reveals that adjacent wall jet collisions cause the boundary layer to rupture and produce secondary stagnation zones, which presents intense turbulence anisotropy. Spectral proper orthogonal decomposition identifies low-frequency coherent structures in collision zones. Heat transfer in collision zones is regulated by the axial velocity gradients and the spanwise Reynolds stress component. The latter intensifies local heat transfer variations. Increasing the number of jets dampens the unsteady behavior of the spanwise-averaged Nusselt number ( Nu ) but intensifies that of the circumferential-averaged Nu . Double/triple jets improve significantly leading-edge area-averaged Nu by 7.07% and 10.48%, respectively, with greater gains in drainage channels caused by elevated coolant flow rates. Flow loss sub-linearly increases with jet count, with the total pressure loss coefficient rising by 3.70% for double jets and 5.71% for triple jets. The Multi-jet IDC design demonstrates superior heat transfer performance and flow stability by leveraging multi-jet synergy and effective coolant management, offering valuable insights for the thermal design of high-efficiency cooling systems.