Gaseous film cooling at various degrees of hot-gas acceleration and turbulence levels

Abstract An experimental and analytical investigation of gaseous film cooling at various rates of hot-gas acceleration and variable free-stream turbulence intensity is presented. The acceleration rate was varied through the convergence angle (0, 30, 45 and 60°) and the free-stream turbulence intensity (3.2–22 per cent) was varied by cross-flow grids upstream of the film coolant slot. The hot-gas stream consisted of 1000°F nitrogen with ambient temperature (70°F) nitrogen used as film coolant. Quantitative results as to detrimental effects of increased free-stream turbulence and wall convergence angle on film cooling effectiveness along converging walls are given. Correlation of the data is accomplished in a form suggested by a newly derived mixing model, which considers compressibility and allows for a variable degree of mixing.

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