The present study focuses on evaluating the thermal performance of the realistic leading edge cooling passage of a turbine blade, experimentally. The detailed heat transfer distributions and pressure loss of the cooling passage are measured with and without rib turbulators for direct comparison.
The experimental model is representing the realistic leading edge cooling passage, which has a converging duct with triangular cross sectional shape. Therefore, the aspect ratio and the cross sectional area of the triangular passage vary significantly along the coolant flow direction. A Perspex test model is designed at 1.3 times large scale to meet Reynolds number similarity. The test model is installed with 45-degree rib turbulators at constant space-to-height ratio of P/e = 10. The experiments are carried out at the Reynolds numbers of 20,000, 40,000 and 80,000. The transient heat transfer test technique using thermochromic liquid crystals (TLCs) was applied to measure the detailed surface heat transfer distributions. The local mixed bulk temperatures (Tmb) are defined using the air thermocouples positioned in the centerline along the cooling passage. The static pressures are measured from the pressure taps machined as a part of the test model so that friction factors of the ribbed cooling passage are also evaluated. The friction factors are influenced by the characteristics of 3 dimensional converging duct of the experimental model. The full surface heat transfer coefficients, friction factors, and overall thermal performance of the cooling passage are reported for the comparison with the other cooling configurations.