Turbine vane cooling system

In a turbine vane comprising a hollow blade (2) radially extending from a vane root (3) to a vane head (4) and including a leading edge (5) and a trailing edge (6) spaced from each other and connected by spaced concave and convex side walls (7, 8) and further including an air cooling system inside the vane that is supplied with cooling air through the vane root (3) and arranged such that the cooling air is directed against the inner surfaces of the side walls, the improvement comprising:

• said turbine vane comprising two radial walls (9, 10) spanning said concave (7) and convex (8) side walls and dividing the inside of said vane (1) into an upstream cooling cavity (11) located near the leading edge (5), a middle cooling cavity (12) located between said radial walls (9, 10) and a downstream cooling cavity (13) located adjacent the trailing edge (6);
• an air intake (22) at the vane root (3) in communication with air exhaust orifices (20, 21) in the vane head (4) for exhausting cooling air from the upstream and middle cavities (11, 12);
• a separate air intake (23) in the vane root (3) in communication with the downstream cavity (13);
• a plurality of exhaust slots (19) in the trailing edge (6) in communication with the downstream cavity for exhausting cooling air from the downstream cavity;
• said cooling system comprising:
• a helical ramp (30) in the upstream cavity extending between the vane root (3) and the vane head (4);
• a lining (40) in the middle cavity (12) in contact with the insides of the radial walls (9, 10) and spaced apart a distance from the side walls (7, 8) of the vane (1) by projecting elements (47) extending from the lining, the lining (40) having a plurality of orifices (41) located opposite the vane side walls (7, 8) for directing cooling air against the side walls (7, 8);
• a transverse wall (17) in the downstream cavity (13) closing the lower end of said downstream cavity (13);
• a third radial wall (14) dividing said downstream cavity (13) into an upstream portion (15) and a downstream portion (16) near the trailing edge (6) of the vane;
• said exhaust slots (19) at the vane trailing edge in communication with said downstream portion (16);
• an aperture (18) at the base of said third wall (14) providing communication between the upstream and downstream portions of said downstream cavity;
• the vane side walls (7, 8) facing the upstream portion comprising double skins (7a, 7b, 8a, 8b) connected by bridging elements (24);
• whereby cooling air fed in at the vane root (3) and flowing between said double skins enters the upstream portion (15) at the vane head (4) and then flows to the downstream portion (16) through said aperture (18) and then is exhausted through said exhaust slots (19).