Patent ID: 6672836
Filing Date: 2004-01-06
Classification: F01D,F05D,Y02T

Abstract:
A coolable rotor blade for an industrial gas turbine engine which has a front flowpath for cooling air and a rear flowpath for cooling air, an airfoil having a leading edge region, a trailing edge region and a midchord region disposed between the leading edge region and the trailing edge region, the airfoil having a suction sidewall and a pressure sidewall which are joined at the leading edge region and at the trailing edge region and spaced apart leaving a cavity therebetween through which at least a portion of the flowpaths for cooling air extend, a front serpentine passage and a rear serpentine passage extending in the cavity which each have an upstream direction and a downstream direction, which each are bounded by the suction sidewall, by the pressure sidewall, and by adjacent airfoil structure extending spanwise and between the walls, each serpentine passage having a first spanwise leg, a second spanwise leg and a third spanwise leg serially connected such that the associated portion of the flowpath extends through the legs for serially flowing a stream of cooling air under operative conditions from the midchord region through the first leg to the third leg in one of said edge regions of the airfoil from which third leg the stream of cooling air is discharged under operative conditions, which comprises:at least one array of trip strips on the suction sidewall and at least one array of trip strips on the pressure sidewall bounding the front serpentine passage, at least one array of trip strips on the suction sidewall and at least one array of trip strips on the pressure sidewall bounding the rear serpentine passage, the arrays of trip strips forming at least two arrays of trip strips for each passage, the trip strips of each array on each sidewall being spaced spanwise one from the other with a pitch and spaced spanwise from and substantially parallel to the adjacent trip strips of the array on the other wall, each trip strip extending into a leg of the associated passage and having a height measured from the adjacent portion of the sidewall and a trip strip height to pitch ratio for that leg, wherein each leg of each serpentine passage which is downstream of another leg has a trip strip height to pitch ratio over at least a portion of the leg which is greater than that of the preceding leg to increase the heat transfer effectiveness of each downstream leg over that of the upstream leg as the cooling air in either serpentine passage moves closer to the associated edge region of the airfoil under operative conditions and wherein the pitch for each of the arrays of trip strips in each leg having trip strips is constant, except for the third leg of the rear serpentine passage, to promote ease of manufacture and inspectability while providing heat removal that emphasizes the edge regions over the midchord region.