Triple-walled impingement insert for re-using impingement air in an airfoil, airfoil comprising the impingement insert, turbomachine component and a gas turbine having the same

Abstract

Impingement insert for an airfoil of a blade/vane of a gas turbine is provided. The impingement insert includes a triple-walled section having a central wall, an outer and an inner peripheral walls, that define—a central channel at an inner surface of the central wall, an inner channel between the central wall and the inner peripheral wall, a middle channel between the inner peripheral wall and the outer peripheral wall, and an outer channel at an outer surface of the outer peripheral wall. Impingement cooling holes are provided in the outer peripheral wall that use the cooling air of the middle channel to eject impingement jets into the outer channel. The impingement insert includes at least one supply duct that fluidly connects the central channel to the middle channel for supplying the cooling air from the central channel to the middle channel, at least one extraction duct that extends between the outer and the inner peripheral walls across the middle channel, and has an inlet at the outer channel, and an outlet at the inner channel, for flowing the cooling air, after impingement, from the outer channel into the inner channel.