An experimental investigation was conducted to determine discharge coefficients for various types of combustor-liner air-entry holes such as flush rectangular holes, step louvers, and scoops. The data presented herein show the variation in discharge coefficient of each configuration as a function of a dimensionless flow parameter. Within the range investi¬gated, the effect of size or shape of flush holes on discharge coefficient was small compared to the effects of duct stream velocity or pressure ratio across the hole. While the addition of a scoop to a flush hole increased the discharge coefficient only at low values of the flow param¬eter, the step louver and the thumbnail-type scoop increased discharge coefficients throughout the range of the flow parameter. However, at low values of the flow parameter, the discharge coefficients for scoops and step louvers were affected by boundary-layer conditions of the duct stream. The proximity of multiple flush holes or the wall inclination of a convergent duct had a negligible effect on discharge coefficient.
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