Film Cooling Effectiveness Comparison on Turbine Vane Endwall With Cluster Configurations Using PSP Measurement Technique

Abstract

Film cooling performance comparison on a turbine vane endwall with two different cluster configurations incorporating upstream inlet leakage flow was studied by applying PSP measurement technique. Experiments were conducted in a blow-down wind tunnel cascade facility at the exit isentropic Mach number of 0.5 corresponding to inlet Reynolds number of 380,000, based on axial chord length. A freestream turbulence level was generated as high as 19% with an integral length scale of 1.7 cm at the inlet of vanes’ leading edge plane. The results of each design and the comparison are presented in two-dimensional adiabatic film cooling effectiveness distributions on the endwall surface as well as the corresponding laterally averaged distributions. The focus of this study is to compare two different endwall cooling designs by the parametric effect of coolant-to-mainstream mass flow ratio (MFR) and density ratio (DR) on film cooling effectiveness. Initially, increased MFR for the endwall cooling and upstream leakage levels up the local film cooling effectiveness and yields improved coverage on the endwall. However, the endwall and upstream leakage demonstrate different behavior, while highest MFR does not provide any improvement as endwall cooling is suffered from the jet lift-off, highest MFR from the upstream leakage shows a monotonic increasing effectiveness on the endwall. On the other hand, the DR effect on effectiveness reveals different trend at a different design. Under a given amount of coolant supply and a fixed number of cooling hole, the comparison results really emphasize the importance of the cooling hole arrangement as one of the proposed cluster design can properly cover the whole endwall area.