Combustor for a gas turbine with cooling structure

Abstract

A combustor/transition piece for a gas turbine including a double walled structure having a plurality of cooling channels, both axially and, in some cases, circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are formed in the area between the inner member of the combustor and the outer member thereof. The passages preferably extend both axially and circumferentially with respect to the direction of flow through the combustor/transition piece. The axial passages extend completely from one end to the other and the circumferential passages extend around the circumference of the combustor/transition piece. The addition of a circumferential cross-flow passage connecting axial flow coolant passages in double wall turbine components can prevent combustor/transition piece part failure due to axial passage inlet blockage without affecting normal, unblocked cooling. Double wall cooling structures are constructed using two unbonded members. The inner member is machined to form cooling passages. Differential thermal expansion (expansion of the outside diameter of the hot inner wall until contact is established with the inside diameter of the cooler outer wall) keeps the cylinders held tightly together. Double wall cooling structures are also constructed using two members shrink-fitted and then bonded together such as by welding. The inner member is machined to form the cooling passages. The improved thermal contact between the outer and inner members due to the joint reduces the thermally induced stresses in the two members.