EFFEECT OF SHAPED HOLES AND DENSITY RATIO ON FILM COOLING EFFICTIVENESS

摘要

Film cooling has become a standard method for the protection of the skin of gas turbine blades against the influence high temperatures of the hot gas stream. The cooling air is usually injected into the boundary layer covering the skin through one or two rows of holes. A calculation method to predict heat transfer to the skin of a film cooled wall based on two parameters the film effectiveness and a heat transfer coefficient defined with the adiabatic wall temperature. Improvements have been made to the shaping of the cooling hole to provide higher heat transfer effectiveness. The present work study effect of the four shapes (1) Cylindrical Hole (REF),(2) Cusp Hole(CUSP), (3) Forward -Diffused Hole(FDIFF) and (4) Laterally-Diffused Hole(LDIFF) on film cooling effectiveness on the adiabatic wall flat plate. The present study of the film cooling to protect from high temperatures through the Parametric study of effect of shapes on the hole cooling, blowing ratio and density ratio on the film cooling effectiveness. Stream wise angle (α) is kept constant at 35 degree and compound (span wise) injection angle (β) is maintained at 90 degree. The series data are collected at fifth blowing ratios (M) = [0.5, 1, 1.25, 1.5 and 2]. The density ratio is constant at 1.97 but it varies from the best shape and blowing ratio at 6, 3, 1.97 and 1.5 Using computational fluid dynamics software FLUENT ® and choosing the standard k-ε model.