Abstract:
A method facilitates assembling a gas turbine engine. The method comprises providing a rotor assembly including a rotor shaft and a rotor disk that includes a radially outer rim, a radially inner hub, and an integral web extending therebetween, wherein the rotor assembly is rotatable about an axis of rotation extending through the rotor shaft, and coupling a disk retainer including at least one discharge tube to the rotor disk wherein the discharge tube extends outwardly from the disk retainer for pumping the air to a higher pressure before discharging cooling fluid therefrom in a direction that is substantially perpendicular with respect to the axis of rotation.

Description:
GOVERNMENT RIGHTS STATEMENT 
     The United States Government has rights in this invention pursuant to Contract No. DAAEO7-00-C-N086. 
    
    
     BACKGROUND OF THE INVENTION 
     This application relates generally to gas turbine engines and, more particularly, to gas turbine engine rotor assemblies. 
     A gas turbine engine typically includes a multi-stage axial compressor, a combustor, and a turbine. Airflow entering the compressor is compressed and directed to the combustor where it is mixed with fuel and ignited, producing hot combustion gases used to drive the turbine. To control the heat transfer induced by the hot combustion gases entering the turbine, typically cooling air is channeled through a turbine cooling circuit and used to cool the turbine. 
     Compressor bleed air is often used as a source of cooling air for the turbine cooling circuit and is also used to purge cavities defined within the engine. More specifically, maintaining sufficient cooling air and purging of air cavities within the gas turbine engine may be critical to proper engine performance and component longevity. However, extracting cooling air from the compressor may affect overall gas turbine engine performance. Balanced with the need to adequately cool components is a desire to maintain high levels of operating efficiency, and as such, generally, because the temperature of air flowing through the compressor increases at each stage of the compressor, utilizing cooling air from the lowest allowable compressor stage results in a lower engine performance decrement as a result of such cooling air extraction. However, within such engines, during at least some engine power settings, the compressor system may fail to provide purge air at a sufficient pressure, and as such hot gases may be still be ingested into the cavities. Over time, continued exposure to such temperature excursions may limit the useful life of components adjacent to the cavities. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect, a method of assembling a gas turbine engine is provided. The method comprises providing a rotor assembly including a rotor shaft and a rotor disk that includes a radially outer rim, a radially inner hub, and an integral web extending therebetween, wherein the rotor assembly is rotatable about an axis of rotation extending through the rotor shaft, and coupling a disk retainer including at least one discharge tube to the rotor disk wherein the discharge tube extends outwardly from the disk retainer for pumping and then discharging cooling fluid therefrom in a direction that is substantially perpendicular with respect to the axis of rotation. 
     In another aspect, a rotor assembly for a gas turbine engine including a centerline axis of rotation is provided. The rotor assembly includes a rotor shaft, a rotor disk, and a disk retainer. The rotor disk is coupled to the rotor shaft and includes a radially outer rim, a radially inner hub, and an integral web extending therebetween. The disk retainer is coupled to the rotor disk and includes at least one discharge tube extending radially outwardly from said disk retainer for pumping and then discharging cooling fluid therefrom in a direction that is substantially perpendicular with respect to the gas turbine engine axis of rotation. 
     In a further aspect, a gas turbine engine including a rotor assembly is provided. The rotor assembly includes a rotor shaft, a rotor disk, and a disk retainer. The rotor shaft has a centerline axis of rotation. The rotor disk is coupled to the rotor shaft and includes a radially outer rim, a radially inner hub, and an integral web extending therebetween. The disk retainer is coupled to the rotor disk and includes at least one discharge tube extending radially outwardly from the disk retainer. The discharge tube pumps and then discharges cooling fluid in a direction that is substantially perpendicular to the rotor shaft axis of rotation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a gas turbine engine; and 
         FIG. 2  is a side cross-sectional schematic illustration of a turbine cooling circuit used with the gas turbine engine shown in FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic illustration of a gas turbine engine  10  including a gear box  12 , a high pressure compressor  14 , and a combustor  16 . Engine  10  also includes a high pressure turbine  18  and a low pressure turbine  20 . Gear box  12  and turbine  20  are coupled by a first shaft  24 , and compressor  14  and turbine  18  are coupled by a second shaft  26 . Accordingly, because shafts  24  and  26  are aligned substantially coaxially, each is rotatable about the same axis of rotation  28 . In one embodiment, the gas turbine engine is an LV100 available from General Electric Company, Cincinnati, Ohio. 
     In operation, air flows through compressor  14 . The highly compressed air is delivered to combustor  16 . Airflow from combustor  16  drives turbines  18  and  20  before exiting gas turbine engine  10 . Work done by turbine  20  is then transmitted to gearbox  12  by means of shaft  24  wherein the available work can then be used to drive a vehicle or generator. 
       FIG. 2  is a side cross-sectional schematic illustration of a turbine cooling circuit  38  that may be used with gas turbine engine  10 . Combustor  16  includes an annular outer liner  40 , an annular inner liner  42 , and a domed end (not shown) extending between outer and inner liners  40  and  42 , respectively. Outer liner  40  and inner liner  42  are spaced radially inward from a combustor casing (not shown) and define a combustion chamber system assembly  46 . An inner nozzle support  44  is generally annular and extends downstream from a diffuser (not shown). Combustion chamber  46  is generally annular in shape and is defined between liners  40  and  42 . Inner liner  42  and inner nozzle support  44  define an inner passageway  50 . Outer and inner liners  40  and  42  each extend to a turbine nozzle  52  positioned downstream from combustor  16 . 
     High pressure turbine  18  is coupled substantially coaxially with compressor  14  (shown in  FIG. 1 ) and downstream from combustor  16 . Turbine  18  includes a rotor assembly  62  that includes at least one rotor  64  that may be formed by one or more disks  66 . In the exemplary embodiment, disk  66  includes a radially outer rim  68 , a radially inner hub  70 , and an integral web  72  extending generally radially therebetween and radially inward from a respective blade dovetail slot  73 . Each disk  66  also includes a plurality of blades  74  extending radially outward from outer rim  68 . Disk  66  extends circumferentially around rotor assembly  62  and each row of blades  74  is sometimes referred to as a turbine stage. 
     An annular forward disk retainer  80  and an annular aft disk retainer  82  extend along dovetail slot  73  to facilitate retaining rotor blades  74  within dovetail slot  73 . Specifically, forward disk retainer  80  extends along an upstream side  84  of disk  66  and includes a radially outer end  110 , a radially inner end  112 , and a body  114  extending therebetween. Body  114  includes a plurality of radially outer seal teeth  120  and a plurality of radially inner seal teeth  122 . Radially outer seal teeth  120  cooperate with a seal member  124  to form an outer balance piston (OBP) seal  126 , and radially inner seal teeth  122  cooperate with a seal member  128  to form an inner balance piston (IBP) seal  130 . An accelerator discharge cavity  134  is defined between IBP seal  130  and OBP seal  126 , and OBP seal  126  is positioned between cooling cavity  134  and an outer balance piston discharge cavity  138 . 
     Aft disk retainer  82  extends along a downstream side  150  of disk  66  and includes a radially outer end  152 , a radially inner end  154 , and a body  156  extending therebetween. Body  156  includes a cooling plate portion  160 , a disk stub shaft portion  162 , and a plurality of radial air pumpers  164  positioned therebetween. Cooling plate portion  160  is coupled against disk  66  with a radial interference fit and extends from retainer outer end  152  to each radial air pumper  164 . Disk stub shaft portion  162  is oriented generally perpendicularly from retainer portion  160  and extends along rotor shaft  26 . More specifically, disk stub shaft portion  162  extends from radial air pumpers  164  to retainer end  154  to facilitate aft disk retainer  82  being coupled to shaft  26  such that a compressive load is induced through shaft portion  162  to retainer  82 . 
     Radial air pumpers  164  are spaced circumferentially within engine  10  and each is oriented substantially perpendicularly to axis of rotation  28 . In the exemplary embodiment, aft disk retainer  82  includes eight radial air pumpers  164 . Each radial air pumper  164  is hollow and includes an inlet  180 , an outlet  182  that is radially outward from inlet  182 , and a substantially cylindrical body  184  extending therebetween. Each radial air pumper  164  has a length L 1  that enables each pumper  164  to extend at least partially into an aft rim cavity  188  bordered at least partially by aft disk retainer  82 . Furthermore radial air pumper length L 1  also facilitates maintaining or accelerating the angular air velocity of air flowing through pumpers  164 , and increasing the discharge pressure of such air relative to a weaker forced vortex pressure rise which would occur without the use of pumpers  164 . 
     Each radial air pumper inlet  180  is coupled in flow communication with a bore cavity  190 . Bore cavity  190  is defined at least partially between disk  66  and shaft  26 . Bore cavity  190  extends axially between, and is coupled in flow communication to, each radial air pumper  164  and to a sump buffer cavity  194 . Sump buffer cavity  194  is also coupled in flow communication to an air source through an annulus  196 , such that air discharged from annulus  196  enters sump buffer cavity  194  prior to being discharged into a sump  200 . As described in more detail below, leakage from sump buffer cavity  194  is channeled to bore cavity  190 . 
     Cooling circuit  38  is in flow communication with an air source, such as compressor  14  and turbine  20  and supplies cooling air from compressor  14  to facilitate cooling turbine  20 . During operation, air discharged from compressor  14  is mixed with fuel and ignited to produce hot combustion gases. The resulting hot combustion gases drive turbine  20 . Simultaneously, a portion of air is extracted from compressor  14  to cooling circuit  38  to facilitate cooling turbine components and purging cavities. 
     Specifically, at least a portion of air extracted from compressor  14  is channeled through an accelerator prior to being discharged into accelerator discharge cavity  134 . Cooling air  209  supplied from sump buffer cavity  194  is channeled into sump  200 . A portion  212  of air  210  supplied to buffer cavity  194  is mixed with air  214  leaking from discharge cavity  134  through IBP seal  130  and is channeled into bore cavity  190 . Leakage of air  212  from sump buffer cavity  194  facilitates preventing ingestion of warm compressor discharge air within sump  200 . More specifically, because air  214  flowing into bore cavity  190  is discharged through pumpers  164 , the operating pressure within bore cavity  190  is decreased, such that pumpers  164  facilitate positively purging cavity  190  and preventing flow  212  from reversing direction. Moreover, because the discharge pressure of air  214  flowing through pumpers  164  is increased, pumpers  164  also facilitate positively purging aft rim cavity  188 . 
     Flow  216  discharged from aft rim cavity  188  is forced radially outwardly between a disk seal assembly  82  and an aft transition duct inner flow path buffer seal  218  to facilitate cooling of outer rotor rim  68  and disk seal assembly  82 . Moreover, purging of cavities  190  and  188  facilitates preventing ingestion of warm compressor discharge therein, which over time, could cause damage to components housed within, adjacent to, or in flow communication with cavities  188  and  190 . 
     The above-described turbine cooling circuit is cost-effective and highly reliable. The cooling circuit includes an aft disk retainer that is formed integrally with a shaft stub portion and with a plurality of radial air pumpers. Because the retainer is formed integrally with a cooling plate portion and a disk stub portion, manufacturing costs, and turbine assembly times are facilitated to be reduced. Moreover, because the radial pumpers increase a discharge pressure of air flowing therethrough, the pumpers facilitate positively purging the aft rim cavity and the bore cavity thus ensuring purge flow from the sump buffer cavity. Accordingly, the pumpers thus facilitate preventing warm compressor dischrage from being ingested within the aforementioned cavities. As a result, the aft rotor retainer assembly and the cooling circuit facilitates extending a useful life of the turbine rotor assembly in a cost-effective and reliable manner. 
     Exemplary embodiments of rotor assemblies and cooling circuits are described above in detail. The rotor assemblies are not limited to the specific embodiments described herein, but rather, components of each assembly may be utilized independently and separately from other components described herein. For example, each aft retainer assembly component can also be used in combination with other cooling circuit components and with other rotor assemblies. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.