Effects of rim seal exit geometry on the cooling characteristics of turbine endwall and blade suction side

For a turbine blade endwall, the leakage (purge flow) exits through rim seal to prevent hot gas ingress and provide some cooling to the endwall. However, changes in the rim seal geometry will inevitably affect the leakage flow over the endwall. To obtain a clearer and quantitative understanding of the effect of rim seal variation on the cooling performance and flow structure, this paper investigated the effects of width and inclined angle of rim seal exit geometry, as well as the flow structure inside the gap and above the passage. A correlation fitting was constructed using the area-averaged cooling effectiveness to quantify the cooling performance on the suction side. The results indicate that the cooling performance of endwall is not sensitive to changes in width. However, a decrease in the inclined angle benefits the inhibition of the cavity vortex, prevents the gas ingress and improves the cooling performance over the endwall. The cooling performance of blade suction side is sensitive to the leakage mass flow ratio. As the mass flow rate increases from 0.5 % to 1.0 % and 1.5 %, the area-averaged cooling effectiveness on suction side for original case increases by 44.4 % and 30.7 %. The correlation established for the cooling of suction side shows a good fit, which provide a possible evaluation method for cooling design.