Patent Publication Number: US-2015069763-A1

Title: Load cover

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a load cover enclosing a coupling between a gas turbine rotor and a generator and, more particularly, to a load cover that provides acoustic attenuation and ventilation flow and encloses a coupling between a gas turbine rotor and a generator. 
     In gas turbine engines, combustion gases are expanded in a turbine section disposed downstream from a combustor to produce mechanical energy. This mechanical energy causes a rotor extending through the turbine section to rotate about a longitudinal axis thereof The rotor extends through the turbine, a compressor and a generator such that the rotation of the rotor causes the compressor to compress inlet gases for use in the combustion and causes the generator to convert the rotation of the rotor to electrical power. 
     With the above-described configuration, a source of acoustic and ventilation issues may be the location where the rotor connects with or is coupled to the generator. In some cases, this region has a fixed duct that produces a cooling flow and has flow control features but generally lacks acoustic attenuation capability. This lack of acoustic capabilities, can lead to reduced efficiencies, performance degradation and economic costs. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a load cover for a coupling between a rotor of a gas turbine engine and a generator is provided. The load cover includes a guard, which is disposed about the rotor, and a baffle disposed around the guard to form an annulus of circumferentially increasing area. The baffle includes a scoop element at an outlet of the annulus. 
     According to another aspect of the invention, a load cover for a coupling between a rotor of a gas turbine engine and a generator is provided and includes a tubular guard, which is disposed about the rotor, and a baffle disposed around the guard to form an annulus of circumferentially increasing area. The baffle is formed to define an inlet at a lower portion of the annulus by which fluid is permitted to enter the annulus and an outlet at an upper portion of the annulus by which the fluid is forced out of the annulus by rotor rotation. The baffle includes a scoop element at the outlet, which is configured to direct fluid egress from the annulus. 
     According to yet another aspect of the invention, a gas turbine engine is provided and includes a turbine section in which an expansion of combustion gases produces mechanical energy, a rotor, which extends through the turbine section, the rotor being drivable to rotate by the mechanical energy, a generator through which the rotor extends, the generator being configured to produce electricity from rotor rotation and a load cover at a coupling between the rotor and the generator. The load cover includes a guard, which is disposed about the rotor, and a baffle disposed around the guard to form an annulus of circumferentially increasing area. The baffle includes a scoop element at an outlet of the annulus. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic diagram of a gas turbine engine in accordance with embodiments; 
         FIG. 2  is a perspective view of a load cover in accordance with embodiments; 
         FIG. 3  is a side view of a load cover in accordance with embodiments; 
         FIG. 4  is an axial view of the load cover of  FIG. 3  along the line  4 - 4 ; and 
         FIG. 5  is an enlarged view of the encircled portion of  FIG. 4 . 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As described below, a load cover that encloses a coupling between a gas turbine rotor and a generator is provided. The load cover has acoustic and flow control features. The acoustic features limit noise generation in the load cover and the flow control features ensure a cooling flow of ambient air, which is produced by the rotation of the coupling inside the load cover. 
     With reference to  FIG. 1 , a gas turbine engine  10  is provided and includes a compressor  11 , a combustor  12  and a turbine section  13 . The compressor  11  is configured to compress inlet air and the combustor  12  is configured to mix the compressed inlet air with fuel and to cause the mixture to combust in an interior thereof This combustion produces a high temperature and high pressure working fluid that is directed toward the turbine section  13 , which is disposed downstream from the combustor  12 . Inside the turbine section  13 , the working fluid is expanded to produce mechanical energy and this mechanical energy causes a rotor  14 , which extends through the compressor  11  and the turbine section  13 , to rotate. The rotation of the rotor  14  drives an operation of the compressor  11 . 
     With reference to  FIGS. 1-4 , the gas turbine engine  10  further includes a generator  15  and a coupling  20 . The rotor  14  extends out of the turbine section  13  and is rotatably coupled to the generator  15  via the coupling  20  such that rotation of the rotor  14  causes the generator  15  to generate electricity for application to a load. 
     As shown in  FIGS. 1-4 , a load cover  30  is provided at the coupling  20  between the rotor  14  and the generator  15  to surround the coupling  20 . The load cover  30  abuts or is disposed proximate to an axial surface  150  of the generator  15  and includes a guard  31 , which is disposed about the rotor  14 , and a baffle  32 . The load cover  30  may further include a wall structure that has access hatches for generator  15  grounding brushes and double layers of mineral wool and vinyl loaded septum structures for acoustic attenuation. 
     The guard  31  and the baffle  32  extend in an axial direction or axially away from the axial surface  150  by a length or distance D (see  FIG. 3 ), which in either case defines an axial length of the load cover  30 . The baffle  32  is disposed about the guard  31  to form an annulus  33  between an exterior surface  310  of the guard  31  and an interior surface  320  of the baffle  32 . The baffle  32  is further formed to define an inlet  34  at a bottom portion of the annulus  33  and an outlet  35  at a top portion of the annulus  33 . The baffle  32  includes a scoop element  36  at the outlet  35 . 
     In accordance with embodiments, the guard  31  may be provided as a substantially tubular element  311  and the interior surface  320  of the baffle  32  may be curved about a central axis  37  defined axially through the load cover  30  and along the rotor  14 . The curvature of the interior surface  320  has an increasing radius of curvature. The increasing radius of curvature provides the annulus  33  with a circumferentially increasing area through which fluids, such as coolant drawn from ambient air, can flow. In accordance with further embodiments, the circumferentially increasing area is measured from about a 12:00 position proximate to the outlet  35  and the top portion of the annulus  33 , past a 6:00 position proximate to the inlet  34  and the bottom portion of the annulus  33  and back to the 12:00 position. 
     Where the fluids include the coolant drawn from ambient air, the ambient air may enter the annulus  33  via the inlet  34  and may exit the annulus  33  via the outlet  35 . The rotation of the rotor  14  drives (or rather pulls) the flow of the air around the exterior surface  310  of the guard  31  and through the annulus  33 . The circumferentially increasing area of the annulus  33  as provided by the increasing radius of curvature of the interior surface  320  of the baffle  32  causes the air to expand as it is driven (or pulled) through the annulus  33 , which promotes the ingress of additional fluid via the inlet  34 . 
     The baffle  32  is formed as a housing  321  with a top portion  322  and a lower portion  323 . The top portion  322  is formed to define an outlet path  324 , which is disposed in fluid communication with the outlet  35  with the outlet  35  being located at an end of the outlet path  324 . The lower portion  323  is formed to define an inlet path  325 , which is disposed in fluid communication with the inlet  34  with the inlet  34  being located at an end of the inlet path  325 . As shown in  FIG. 4 , the outlet path  324  includes a serpentine outlet path  326  and the inlet path  325  includes a serpentine inlet path  327 . The serpentine outlet path  236  and the serpentine inlet path  327  serve to reduce a pressure of the air in the baffle  32  and to reduce noise associated with the flow of the air through the baffle  32 . In this way, at least one or both of the serpentine outlet path  236  and the serpentine inlet path  327  may act as a silencer for the load cover  30 . 
     The scoop element  36  extends axially along the guard  31  and includes a curved surface  360 . The curved surface  360  facilitates the flow of air from the end of the annulus  33 , through the outlet  35  and into the outlet path  324 . That is, the scoop element  36  is configured to direct fluid egress from the annulus  33 . To this end, the scoop element  36  may extend into the annulus  33  in a curved or straight configuration. Where the scoop element  36  is curved, the curvature may be oriented in an opposite direction from the curvature of the interior surface  320  of the baffle  32 . In accordance with embodiments, a radius of curvature of the curved scoop element  36  may be about  50  mm although this is certainly not required and should not be interpreted as limiting a scope of this disclosure in any way. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.