EXPERIMENTAL AND NUMERICAL STUDY OF NEAR BLEED HOLE HEAT TRANSFER ENHANCEMENT IN INTERNAL TURBINE BLADE COOLING CHANNELS

An experimental and numerical investigation was conducted to determine local heat transfer enhancement near the entrance to a single film cooling hole. The purpose of the investigation was to determine and compare the effects of bleed hole suction ratio and extraction angle on the augmented heat transfer (near the hole entrance) to experimental results previously obtained with liquid crystal thermometry at lower temperature ratios. Steady state heat transfer results were acquired by using a transient measurement technique in an 80×actual size rectangular channel with thin film measuring gauges concentrated downstream of the bleed hole entrance. The Reynolds number, based on duct hydraulic diameter and bulk mean velocity, was kept constant at 2.5×104, while the hole suction ratio in terms of Reynolds number was varied from 0 to 5