Numerical investigation on blade leading edge high-efficiency swirl and impingement phase transfer cooling mechanism

A comparative study of the flow field and heat transfer characteristics between swirl and impingement of mist/air cooling on blade leading edge is carried out to find a better cooling configuration for phase transition cooling. The Eulerian-Lagrangian particle tracking technique is used to investigate mist/air cooling. Comparisons are made between these two cooling forms in such aspects as vortex structure, heat transfer enhancement, pressure loss, and thermal uniformity with and without mist injection. The influences of mist ratio and Reynolds numbers on these parameters are studied in this paper. Results show that heat transfer is enhanced while pressure loss and thermal uniformity are improved by the swirl flow created by vortex impingement. The heat transfer performance increases by about 46.2 and 51.9%, respectively, for impingement and swirl cooling with 8% mist injection, and the pressure loss coefficient increases by 19%. The difference of heat transfer coefficient between swirl and impingement cooling with and without mist injection at high Reynolds number is larger than that at low Reynolds number. In addition, the heat transfer nonuniform coefficient of swirl cooling is about 15% lower than for impingement cooling.