Cooling-air injection casing for a turbomachine turbine

A cooling air injection casing for cooling a bladed rotor disc of a turbine of a turbomachine,

• wherein the cooling air injection casing extends around a longitudinal axis and is traversed by at least one channel forming an air injector, the at least one channel comprising an inlet mouth and an outlet mouth,
• wherein the at least one channel comprises a primary segment which extends in an axial plane from the inlet mouth of the at least one channel to an elbow and a secondary segment which extends from the elbow to the outlet mouth of the at least one channel, the secondary segment having a gradual variation in the orientation of the secondary segment along a tangential component between a section of the elbow and an outlet section of the outlet mouth,
• wherein the outlet mouth of the at least one channel has an outlet section which extends tangentially and in a plane perpendicular to the longitudinal axis of the cooling air injection casing,
• wherein the elbow is oriented such that the air stream exiting the outlet mouth circulates tangentially to the annular cooling air injection casing
• wherein the at least one channel has a reduction in section between an inlet section of the inlet mouth and a section of a neck,
• wherein the at least one channel has at least one corrugation in the primary segment of the at least one channel, such that the outlet mouth of the at least one channel is located nearer to the longitudinal axis of the cooling air injection casing than the inlet mouth,
• wherein the casing comprises:
• a flared annular outer wall flared from upstream to downstream,
• a radially inner wall which extends downstream from the flared annular outer wall and which supports a radially inner sealing device,
• a radially outer wall which extends from the flared annular outer wall, and
• an end wall which joins a downstream end of the radially inner wall and a downstream end of the radially outer wall the end wall extending in a plane perpendicular to the longitudinal axis of the cooling air injection casing,
• wherein the flared annular outer wall, the radially inner wall, the radially outer wall and the end wall together delimit an annular inner cavity,
• wherein the at least one channel is disposed at least in part in the inner cavity,
• and wherein the outlet mouth of the at least one channel is formed in the end wall.