Film cooling effectiveness predictions in the region of the blade-endwall junction corner with injection assisted by the recirculating vortex flow

摘要

The region around the blade leading edge-endwall junction in inlet guide vanes (IGV) of gas turbines presents one of the most difficult hot spots to be cooled within the blade passage, largely due to the presence of strong three dimensional flows which displace the coolant away from the region before it can provide adequate cooling. The present study investigates via RANS-based simulation the film cooling effectiveness of a novel slot injection in which the coolant is ejected in such a way that its cooling effectiveness is assisted by the presence of the local three dimensional flows (especially the horseshoe vortex) that dominate the junction area. The computational predictions indicate that the proposed injection geometry provides a very effective cooling method for addressing the high heat transfer rate around the problematic region. The predicted three-dimensional flow topology and the associated endwall heat transfer are presented and discussed in order to elucidate the physical mechanisms that lead to the successful film cooling effectiveness of the proposed injection slot.