Coolable segment for a turbomachine and combustion turbine

A coolable segment for a turbomachine operated with a hot fluid, the segment comprising:

• a cooling wall extending in an axial direction and a circumferential direction orthogonal to said axial direction;
• a hot fluid wall generally parallel with the cooling wall, the hot fluid wall comprising an inner surface exposed to said hot fluid;
• a cooling chamber formed between the cooling wall and the hot fluid wall;
• a first cooling fluid supply passage for supplying a cooling fluid into the cooling chamber;
• a first cooling fluid exit aperture for releasing the cooling fluid from the cooling chamber;
• a cooling structure comprising a fibrous or porous material filling the cooling chamber between said cooling wall and said hot fluid wall so that the cooling fluid flowing through the cooling chamber must pass through the cooling structure, the cooling structure being permeable to the cooling fluid and providing cooling surfaces for cooling by heat transmission through radiation;
• a partition wall generally parallel with the cooling wall, the partition wall dividing the cooling chamber into a cooling flow labyrinth between the hot fluid wall and the cooling wall;
• the first cooling fluid supply passage opening into the cooling chamber at a starting point of the labyrinth;
• and
• the first cooling fluid exit aperture opening into the cooling chamber at an ending point of the labyrinth, such that the cooling flow is routed along an inner surface of the cooling wall and an outer surface of the partition wall in a first cooling flow direction then is reversed by the labyrinth and routed along an outer surface of the partition wall and an inner surface of the hot fluid wall in a second cooling flow direction.