US Patent 8683813 Multi-lobed cooling hole and method of manufacture

A gas turbine engine component includes a wall having first and second wall surfaces and a cooling hole extending through the wall. The cooling hole includes an inlet at the first wall surface, an outlet at the second wall surface, a metering section extending downstream from the inlet and a diffusing section extending from the metering section to the outlet. The diffusing section includes a first lobe diverging longitudinally and laterally from the metering section, a second lobe adjacent the first lobe and diverging longitudinally from the metering section, a third lobe adjacent the second lobe and diverging longitudinally and laterally from the metering section, and a transition region having an end adjacent the outlet and a portion that extends between the lobes and the outlet. The first and third lobes each include a curved outer portion.