An experimental investigation has been carried out to determine the heat/mass transfer coefficient downstream of a two-dimensional, normal, film cooling injection slot. The plate downstream of the slot is porous, and air contaminated with propane is bled through it. By measuring the propane concentration very close to the wall using a flame ionization detector, mass transfer measurements are conducted for film cooling mass flow ratios ranging from 0 to 0.5. The mass transfer coefficients are calculated using a wall function correction formula, which corrects the measurements for displacement from the surface, and are then related directly to corresponding heat transfer coefficients using the mass/heat analogy. The validity of the method and the wall function correction formula are checked by examining the case with zero film coolant injection, a situation analogous to the well-known turbulent boundary layer mass/heat transfer with impermeable/unheated starting length. Good agreement with predicted data is obtained for this experiment. For film cooling with low mass flow ratios, heat transfer coefficients close to those of a conventional turbulent boundary layer are obtained. At high values of mass flow ratios quite different trends are observed, reflecting the important effect of the separation bubble, which is present just downstream of the injection slot.
An Experimental Investigation of Film Cooling Heat Transfer Coefficients Using the Mass/Heat Analogy
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Sun, Y., Gartshore, I. S., and Salcudean, M. E. (November 1, 1995). "An Experimental Investigation of Film Cooling Heat Transfer Coefficients Using the Mass/Heat Analogy." ASME. J. Heat Transfer. November 1995; 117(4): 851–858. https://doi.org/10.1115/1.2836301
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