Experimental Study of the Iso-Heat-Transfer-Rate Lines on the End-Wall of a Turbine Cascade

Experiments were conducted to study the distribution of the iso-heat-transfer-rate lines on the end-wall of a turbine cascade. A light piston isentropic compression tube facility was used for the experiments together with thin film heat transfer gages and a fast response analog recording system. The conditions fully represented typical Mach and Reynolds numbers, temperature ratio as well as the blade section of a modern cooled turbine. Special attention was paid to the need for good spatial resolution. The study includes the effect of the free-stream turbulence intensity level and the inlet boundary layer thickness. A subsonic compressible flow calculation method was used to predict the potential flow streamlines and a visualization method was used to study the limiting streamlines on the end wall. Furthermore, the distribution of various heat transfer parameters (e.g., qω, St) along these streamlines have undergone detailed study and some uniformity is shown to exist.