Film coolant passage with swirl diffuser

Claim 1

A hollow, longitudinally extending airfoil including a cooled wall having an outer surface defining a pressure and suction surface of said airfoil, said pressure and suction surfaces adapted to have a hot gas stream flowing thereover in a downstream direction substantially perpendicular to said longitudinal direction, said cooled wall also having an inner surface adapted to define a portion of a coolant compartment for receiving coolant therein under pressure, the improvement comprising: a longitudinally extending cylindrical diffuser channel formed within said wall defining a cylindrical surface and having an axis; a pair of spaced apart, facing side surfaces forming a slot within said wall, said side surfaces intersecting said outer surface at a shallow angle to form a longitudinally extending slot outlet, and intersecting said channel cylindrical surface to form a slot inlet extending longitudinally substantially the full length of said cylindrical channel, said slot being oriented to direct coolant fluid therefrom as a continuous, longitudinally extending film over said outer surface downstream of said slot outlet; a single one of said slots intersecting each channel; and at least one metering passage formed within said wall for controlling the rate of flow of coolant fluid into said slot, said metering passage intersecting said inner surface of said wall to form an inlet for said metering passage and intersecting said diffuser channel cylindrical surface to form an outlet for said metering passage, said metering passage being oriented to direct coolant fluid into said diffuser channel so as to impart a swirling motion to the fluid about the axis of said channel.