Cross-flow film cooling passages

A cooled wall having an outer surface adapted to be exposed to a hot gas stream flowing in a downstream direction over said outer surface, and an inner surface adapted to define a portion of a coolant compartment for receiving coolant therein under pressure, the improvement comprising:

• a coolant passage within said wall, said passage including a metering section and a diffusing section in series flow relation, said metering section having an inlet adapted to receive a flow of coolant from the coolant compartment and adapted to control the rate of flow of coolant fluid through said passage, said metering section including a straight portion having a central axis, said central axis forming a shallow angle with said outer surface of said wall and forming a projected angle of between 20.degree. and 90.degree. with the downstream direction in a plane substantially tangent to said outer surface at said coolant passage outlet, said diffusing section including an upstream side surface parallel to the central axis and a downstream side surface spaced from and facing said upstream side surface and diverging from said upstream side surface toward said passage outlet at a first angle, said diffusing section also including an upstream end surface parallel to the central axis and a downstream end surface spaced from and facing said upstream end surface and diverging from said upstream end surface toward said passage outlet at a second angle, said upstream and downstream end surfaces interconnecting said upstream and downstream side surfaces, said side surfaces and end surfaces intersecting said outer surface to define said passage outlet.