Experimental study of film cooling characteristics of annular cascade endwall with a partitioned film cooling layout

Based on the heat transfer characteristic of the endwall and the distribution law of the turbine cascade vortex system, a partitioned film cooling layout was proposed on an annular cascade endwall. By the passage vortex liftoff line and the passage throat line, the endwall is divided into four regions, which were respectively upstream passage wedge region, upstream pressure side region, downstream pressure side region, and downstream passage wedge region. The endwall film cooling performances of the leakage flow and the partitioned film holes were studied experimentally by the PSP technique. Results indicate that the upstream passage wedge region can be cooled highly when the MFR of leakage flow is more than 1%. Owing to the film superposition effect, the eta of the upstream pressure side region is lower than that of two downstream partitions. As the increased coolant MFR, the eta of the upstream partition was increased, however, there was an opposite trend for the downstream partition. In addition, it is found that the leakage flow enhanced dramatically the film cooling characteristics of the partitioned film holes on the region of X/C-ax <= 0.5 in the study of endwall full-coverage film cooling.