Numerical investigation on the flow and heat transfer in swirl chambers with distributed multi exit slots and dimple/protrusion structure

Swirl cooling is an excellent candidate for internal cooling of turbine blade leading edge. In this paper, a novel swirl chamber with distributed multi exit slots is proposed, for which different outlet configurations are considered. Flow and heat transfer characteristics are numerically investigated and compared with those of conventional chamber. Then dimples/protrusions are innovatively introduced into the swirl chamber, with various arrangements. The influence of temperature ratio is further discussed. The results show that, a typical flow structure of "inner vortex + outer vortex" is formed in the jet regions. In novel swirl chambers, the extraction effect of exit slots avoids the formation of crossflow, thus the friction can be effectively reduced while the heat transfer is strengthened, for which a 46.9% improvement of overall thermal performance (TP) is achieved. The dimple/protrusion can realize the local flow control, and produce a 54.8% improvement in TP. The nozzle-side arrangement of dimple/protrusion is better than the slot-side arrangement, and the protrusion is superior to the dimple. With the increase of temperature ratio, the TP shows the variation trend of increasing first and then decreasing. This research will provide important data support for the internal cooling design of turbine blade leading edge.