Assembly for turbine

An assembly for a turbine of a turbine engine, comprising:

• a casing;
• and
• an annular duct surrounding the casing and extending along an axial direction of the turbine engine, the annular duct being capable of being connected to means for supplying cooling air, and the annular duct having a radially inner annular wall provided with openings arranged opposite an outer surface of the casing in order to cool said casing by the impact of cooling-air jets,
• wherein the casing has a plurality of axial grooves extending in the axial direction and comprising first grooves and second grooves arranged in alternation in a circumferential direction, wherein each first groove is adjacent to the two second grooves consecutive thereto such that each of the first grooves has a circumferential end in common with a circumferential end of one of the second grooves,
• wherein the openings are distributed in a plurality of annular rows extending in the circumferential direction, the plurality of annular rows being spaced apart in the axial direction,
• wherein any pair of consecutive annular rows in the axial direction is such that the openings of one of the annular rows of the pair are centered relative to the first grooves, while the openings of the other annular row of the pair are centered relative to the second grooves such that each opening of the one of the annular rows of the pair is circumferentially offset to two consecutive openings of the other annular row of the pair closest to the each opening, and
• wherein a minimum centerline distance between the openings is 1.6 mm.