Patent Application
20120063916
The present application relates generally to gas turbine engines and more particularly relates to turbine blade platform cooling systems so as to cool the suction side of adjacent blade platforms.
Known turbine assemblies generally include rows of circumferentially spaced turbine blades. Generally described, each turbine blade includes an airfoil extending outwardly from a platform and a shank with a dovetail extending inwardly therefrom. The dovetail is used to mount the turbine blade to a rotor disc for rotation therewith. Known turbine blades generally are hollow such that an internal cooling cavity may be defined through at least portions of the airfoil, the platform, the shank, and the dovetail.
Temperature mismatches may develop at the interface between the airfoil and the platform and/or between the shank and the platform because the airfoil portions of the blades are exposed to higher temperatures than the shank and the dovetail portions. Over time, such temperature differences and associated thermal strains may induce large compressive thermal stresses to the blade platform. Moreover, the increased operating temperatures of the turbine as a whole may cause oxidation, fatigue, cracking, and/or creep deflection and, hence, a shorten useful life for the turbine blade. The potential stresses to the overall turbine blade and the bucket platform in particular generally increase with higher turbine combustion temperatures.
There is thus a desire for a turbine blade with improved cooling, particularly about the suction side of the platform. Such an improved turbine blade design would allow for the use of higher combustion temperatures and, hence, higher overall system efficiency with increased component lifetime.
The present application thus provides a turbine blade cooling system. The turbine blade cooling system may include a first turbine blade with a first turbine blade platform having a cooling cavity in communication with a pressure side passage and a second turbine blade with a second turbine blade platform having a platform cooling cavity with a suction side passage. The pressure side passage of the first turbine blade platform is in communication with the suction side passage of the second turbine blade platform.
The present application further provides a method of cooling a turbine blade platform. The method may include the steps of flowing a cooling medium through a pressure side passage of a first turbine blade platform, flowing the cooling medium through a suction side passage of a second turbine blade platform, flowing the cooling medium through a platform cooling cavity in the second turbine blade platform, and cooling the second turbine blade platform.
The present application further provides a turbine blade platform. The turbine blade platform may include a pressure side passage, a cooling circuit in communication with the pressure side passage, a suction side passage, and a platform cooling cavity in communication with the suction side passage.
These and other features and improvements of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
The gas turbine engine 10 may use natural gas, various types of syngas, and other types of fuels. The gas turbine engine 20 may be one of any number of different gas turbines offered by General Electric Company of Schenectady, N.Y. or otherwise. The gas turbine engine 10 may have other configuration and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines 10, other types of turbines, and other types of power generation equipment may be used herein together.
The turbine blade 50 also may include a shank 85 and a dovetail 90 extending inwardly from the platform 60. A number of angel wings 86 may be attached to the shank 85. The dovetail 90 may attach the turbine blade 50 to a disc (not shown) for rotation therewith. The shank 85 may be substantially hollow with a shank cavity 95 therein. The shank cavity 95 may be in communication with a cooling medium such compressor discharge air. Other types of cooling circuits and cooling mediums also may be used herein. The cooling medium may circulate through at least portions of the dovetail 90, the shank 85, the platform 60, and into the airfoil 55. Other configurations may be used herein.
Each turbine blade 110 may include a platform 150 with an airfoil 160 extending outwardly therefrom and a shank 170 extending inwardly therefrom. The platform 150 may have a forward side 152, an aft side 154, a suction side 156, and a pressure side 158.
The turbine blade 110 may include a cooling cavity 180 extending therethrough. The cooling cavity 180 may be in communication with a cooling medium 190 such as compressor discharge air and the like. The cooling cavity 180 may extend at least in part through the shank 170 and into the airfoil 160. A portion of the cooling cavity 180 also may extend into the platform 150 such that at least a portion of the cooling medium 190 may pass therethrough, either instead of or after passing through the airfoil 160. Specifically, the cooling cavity 180 may extend into the aft portion 154 of the platform 150 about the pressure side 158 thereof. The portion of the cooling cavity 180 may end about a pressure side passage 200 of the platform 150. Other configurations may be used herein.
The platform 150 also may include a platform cooling cavity 210. The platform cooling cavity 210 may extend from the suction side 156 of the platform 150 towards the aft side 154. The platform cooling cavity 210 may begin about a suction side passage 220. The suction side passage 220 may align with the pressure side passage 200 of the adjoining turbine blade 110 so as to pass the cooling medium 190 therethrough. The platform cooling cavity 210 also may include an aft side passage 230 so as to discharge the cooling medium 190 once it passes therethrough. The platform cooling cavity 210 also may include a pin bank or other types of turbulators 240 therein so as to provide turbulence for enhanced heat transfer. Other types of internal configurations may be used herein.
In use, the cooling medium 190 passes through the cooling channel 180 of the first turbine blade 120. At least a portion of the cooling medium 190 passes through the platform 150 and exits via the pressure side passage 200. The cooling medium 190 then passes through the gap 140 and into the platform cooling cavity 210 of the second turbine blade 130. Specifically, the cooling medium 190 passes into the suction side passage 220 of the platform cooling cavity 210 positioned on the suction side 156 of the platform 150 along the aft end 154 thereof. The cooling medium 190 then may exit the platform 150 along the aft side passage 230.
The turbine blade platform cooling system 100 thus provides cooling on the suction side 156 of the platform 150 of the second turbine blade 130 via the cooling medium 190 from the first turbine blade 120. The pin bank or other types of turbulators 240 within the platform cooling cavity 210 also provide enhanced heat transfer therein. This cooling also provides some lateral flexibility between the cooler shank side and the hot gas side of the platform 150 so as to reduce thermal stresses therein. Surface film holes and the like also may be used herein in communication with the platform cooling cavity 210. Various types of seals also may be used about the gap 140 to reduce leakage and ingestion therethrough.
The turbine blade platform cooling system 100 thus provides platform cooling to enable higher turbine operating temperatures so as to provide higher efficiencies and lower customer operating costs with less impact on component durability. Using the cooling medium 190 from the first blade 120 so as to cool the second blade 130 further increases such overall efficiency. Transfer of the cooling medium 190 also may be made from the suction side 156 to the pressure side 158 in a similar manner. Any type of platform to platform cooling schemes in any direction may be used herein.
It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
