Measurements of mass transfer coefficient and effectiveness in the recovery region of a film-cooled surface |
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Affiliation: | 1. Free University of Bozen-Bolzano, Faculty of Sciences and Technology, Piazza Università 5, 39100 Bolzano, Italy;2. University of Genova, Department of Civil, Chemical and Environmental Engineering, Via Opera Pia 15, 16145 Genova, Italy |
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Abstract: | Mass transfer coefficients and film cooling effectiveness are measured downstream of a single row of holes (recovery region) inclined 30° with the surface and inline with the main turbulent boundary layer flow. The mass transfer coefficients are measured using a naphthalene sublimation technique. The effectiveness is determined through the injection of a trace gas into the secondary flow and measuring its concentration at the impermeable wall. Experiments are carried out in a subsonic, zero pressure gradient turbulent boundary layer, under isothermal conditions with three blowing ratios (Uj/U∞): 0.4, 0.8, and 1.2. The data is collected in a region 7–80 jet diameters downstream of the injection location. From the data on mass transfer coefficients and effectiveness obtained under the same flow conditions a general mass transfer equation is derived. This paper presents extensive data and discussions; and is believed to be one of the few studies in which both of these variables are measured on the same surface and in a large area in the recovery region. |
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