Abstract

To study the film cooling performance of impingement-effusion structures, it is important to study their adiabatic film cooling effectiveness. To improve the adiabatic film cooling effectiveness on a vane, some rows of cylindrical effusion holes are changed into fan-shaped holes. This experiment measured the adiabatic film cooling effectiveness of the double-walled system on the suction surface via the pressure-sensitive paint (PSP) technique. The film cooling effectiveness obtained by the PSP technique is coupled with the transient liquid crystal (TLC) technique to determine the heat transfer coefficient. This combination of techniques reduces the time required for the experiment and improves the efficiency of the experiment. The heat transfer coefficient ratio is used to evaluate the level of heating transfer. The net heat flux reduction (NHFR) is used to quantify the net benefit of film cooling. Two experimental vanes’ (A and B) film holes are both arranged in 6 rows of holes. There are 15 holes in each row. Only the positions of the fan-shaped holes are different. The experimental conditions include the mainstream Reynolds number (Re = 151,000) based on the chord length and inlet velocity, the turbulence intensities (Tu = 0.77%, 16.9%), and the mass flux ratios (ṁc/ṁg = 0.4%, 0.8%, 1.6%).

The findings show that when the mass flux ratio increases to a point, the film cooling effectiveness does not improve. Increasing the turbulence intensity leads to a decrease in the film cooling effectiveness except for the region after Row 6 on Vane B. Using the coupling of PSP and TLC to determine the heat transfer coefficient can yield credible results. The turbulence intensity and the arrangement of the film holes have obvious effects on the distribution of the heat transfer coefficient ratio. The effects of turbulence intensity, mass flux ratio and hole arrangement on NHFR were studied.

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