STUDY ON THE IMPINGEMENT COOLING STRUCTURE WITH THE CHARACTERISTIC OF LOW FLOW RESISTANCE

As an efficient cooling method, the impingement cooling in the mid-chord of the aero-engine turbine vane causes the jet to impact the target plate, resulting in a thin boundary layer near the stagnation point and high heat transfer, which other aero-engine internal cooling technologies cannot achieve. Adding pin fins to the target plate is a standard method to improve impingement cooling, but it reduces the coolant flow area in the impingement chamber to increase the flow resistance. This paper proposes a novel structure with low resistance characteristics by adding V-ribs to the target plate. The novel structures' flow and heat transfer characteristics are studied through numerical simulations and experiments. The Reynolds Averaged Naiver-Stokes (RANS) model is adopted for the 3-D steady-state numerical simulation, and the shear stress transport (SST) k-ω turbulence model is used for closing the governing equations. The main conclusions are that the jet Reynolds number (Rej) and the flow-pitch of the impingement hole are critical factors that affect heat transfer, and the change in the jet-to-plate distance can significantly influence flow resistance. As the jet Reynolds number increases from 2000 to 15000, the average Nusselt number on the impingement target surface increases by a factor of 3.6. The flow coefficient at an impingement distance of 3 is 1.45 times that at an impingement distance of 1. The increase in the jet Reynolds number and the reduction in the flow-pitch of the impingement hole enhance the heat transfer on the target plate by increasing the impingement and wall jet velocities respectively, thereby enhancing the scouring effect. The decrease in pressure in the intake chamber and the corresponding decrease in the pressure gradient in the impingement chamber are the main reasons for the decrease in flow resistance caused by the enlargement of the jet-to-plate distance.