Experimental Measurement of Endwall Aerothermal Performance with Various Slashface Configurations in a Transient Test Facility

Abstract To accommodate installation flexibility, metal thermal expansion and components vibration, a clearance, referred to as a slashface gap, always presents between adjacent blade endwalls. Sufficient coolant is fed into this gap to prevent high-temperature gas ingestion, thereby avoiding the overheating risks of blade root and wheel component. Nevertheless, the phenomenon of gas ingestion into the slashface upstream and leakage egestion away from slashface downstream is common, due to endwall axial static pressure gradients. This may result in significant differences in metal thermal expansion during actual operation of gas turbines, thereby developing downsized gaps. Aiming to present insights into leakage flow physics and associated endwall aerothermal performance with non-uniform slashface, various narrower upstream slashface geometries were designed, and endwall heat transfer coefficient (h) and film cooling effectiveness (η) were measured in a novel transient test facility. In addition, to further help understand near-endwall flow behavior and flow patterns at the slashface interface, the supportive numerical predictions were also performed at the same flow conditions. Results demonstrated that there are four typical flow behavior parts from slashface leading edge to trailing edge, identified as gas ingestion region, gas egestion region, interaction region and leakage egestion region.