Abstract:
A flow control module for a turbomachine includes an inlet extending to an outlet through a flow passage having at least one side wall. A flow control member is arranged within the flow control module. The flow control member is secured to the at least one side wall between the inlet and the outlet. The flow control member is selectively passively activated to extend into the flow passage to block cooling fluid passing through the flow control module.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a passively controlled flow control module that guides a cooling fluid flow toward a turbine rotor shaft. 
         [0002]    Gas turbomachines include rotating components that may be subjected to high temperatures. In a turbine, rotor components are subjected to high temperatures and temperature gradients that may have a detrimental effect on system performance and durability. In order to enhance system performance and extend component life, turbomachines include cooling air systems that deliver compressor discharge air toward the rotor components. Typically, the compressor discharge air is passed from a compressor discharge plenum onto a turbomachine rotor. Rotation of the rotor imparts movement to the compressor discharge air resulting in migration toward other rotor components. Rotating component cooling needs vary for various operating conditions. During part load operation, less cooling may be required. Also, less cooling may be required when ambient air temperatures are lower than normal operating conditions. 
         [0003]    Current systems for delivering cooling air toward the rotor include direct injection of compressor discharge air to the rotor, and passing the compressor discharge air through a plurality of injectors distributed about a longitudinal axis of the turbomachine. Direct injection does not provide much control over the compressor discharge air. That is, direct injection does not provide much flexibility in varying the compressor discharge air to accommodate various operating conditions. Injectors can be controlled to change delivery of the cooling air based on operating conditions. In some cases, a bimetallic strip is incorporated into the injector to control air flow. Changes in temperature cause the bimetallic strip to expand and contract thereby changing a discharge opening and altering cooling flow delivery. Often times, the bimetallic strip pivots a trailing edge portion of the injector to control cooling flow delivery. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the exemplary embodiment, a flow control module for a turbomachine includes an inlet extending to an outlet through a flow passage having at least one side wall. A flow control member is arranged within the flow control module. The flow control member is secured to the at least one side wall between the inlet and the outlet. The flow control member is selectively passively activated to extend into the flow passage to block fluid passing through the flow control module. 
         [0005]    According to another aspect of the exemplary embodiment, a turbomachine includes a compressor portion having a compressor discharge, and a turbine portion having a first stage. The first stage includes a wheel space portion, a shaft extending through the wheel space portion, a rotor mounted to the shaft, and at least one bucket mounted to the rotor. A flow control module is arranged down stream from the compressor discharge and upstream from the first stage of the turbine. The flow control module includes an inlet extending to an outlet through a flow passage having at least one side wall. The inlet is fluidly connected to the compressor discharge and the outlet is fluidly connected to the wheel space portion. A flow control member is arranged within the flow control module. The flow control member is secured to the at least one side wall between the inlet and the outlet. The flow control member is selectively passively activated to extend into the flow passage to block cooling fluid passing through the flow control module. 
         [0006]    According to yet another aspect of the exemplary embodiment, a method of passively controlling flow passing from a compressor discharge toward a turbine rotor includes guiding an air flow from a compressor discharge toward a flow control module positioned upstream of a turbine wheel space, passing the air flow through a flow passage extending through the flow control module, and collapsing a first side wall forming the flow passage toward a second side wall forming the flow passage to constrict the flow control module based on a characteristic of the air flow. 
         [0007]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    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: 
           [0009]      FIG. 1  is a partial cross-sectional view of a turbomachine including a flow control module in accordance with an exemplary embodiment; 
           [0010]      FIG. 2  is a perspective view of a flow control module including a flow control member in accordance with an exemplary embodiment; 
           [0011]      FIG. 3  is cross-sectional view of the flow control module of  FIG. 2  illustrating the flow control member in a first position; 
           [0012]      FIG. 4  is a cross-sectional view of the flow control module of  FIG. 2  illustrating the flow control member in a second position; and 
           [0013]      FIG. 5  is a cross-sectional view of a flow control module in accordance with another aspect of the exemplary embodiment. 
       
    
    
       [0014]    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 
       [0015]    With reference to  FIG. 1 , a turbomachine constructed in accordance with an exemplary embodiment is indicated generally at  2 . Turbomachine  2  includes a compressor portion  4  and a turbine portion  6 . Compressor portion  4  includes a compressor housing  8  and turbine portion  6  includes a turbine housing  10 . Compressor portion  4  is linked to turbine portion  6  through a common compressor/turbine shaft or rotor  16 . Compressor portion  4  is also linked to turbine portion  6  through a plurality of circumferentially spaced combustor assemblies, one of which is indicated at  20 . Combustor assembly  20  is fluidly connected to turbine portion  6  by a transition piece  24 . Compressor portion  4  includes a compressor discharge plenum  27  that leads to a diffuser  30 . 
         [0016]    Compressed air flows from compressor portion  4  into compressor discharge plenum  27  passes through diffuser  30  and into combustor assembly  20 . The compressed air mixes with fuel to form a combustible mixture that is combusted to form hot gases. The hot gases flow through transition piece  24  along a hot gas path (not separately labeled) toward a first stage  32  of turbine portion  6 . In addition to passing to combustor assembly  20 , a portion of the compressed air forms an air flow that is passed to a wheel space  34  in turbine portion  6 . In accordance with one aspect of the exemplary embodiment, the air flow represents cooling air passing into turbine portion  6 . 
         [0017]    In accordance with an exemplary embodiment, the air flow passes from diffuser  30  through a flow control module  40  into wheel space  34 . As best shown in  FIGS. 2-3 , flow control module  40  includes an inlet  44  that leads to an outlet  45  through a flow passage  47 . Flow passage  47  includes first and second opposing side walls  53  and  54  that are joined by third and fourth opposing side walls  56  and  57 . First side wall  53  includes a curvilinear surface portion  59 . Similarly, second side wall  54  includes a curvilinear surface portion  60 . Third and fourth side walls  56  and  57  include substantially linear surfaces  62  and  64  respectively. Curvilinear surface portions  59  and  60  are shaped so as to guide the cooling flow from diffuser  30  into wheel space  34  at a desired angle. More specifically, curvilinear surfaces  59  and  60  guide the cooling flow into wheel space  34  so as to pass tangentially across rotor  16 . The air flow is guided in a direction corresponding to a direction of rotation of rotor  16 . By introducing the air flow in the direction of rotation, losses that would otherwise be associated with the cooling flow impacting rotor  16  at a substantially perpendicular angle are reduced. 
         [0018]    When operating at peak or near peak output, air flow through flow control module  40  is unimpeded so as to enhance cooling. However, during off-peak operation, the amount of air flow passing into wheel space  34  can be reduced. Reducing the amount of air flow passing into wheel space  34  leads to an increase in air flowing to combustor assembly  20  which, in turn, leads to increased operational efficiency at off-peak operation. Accordingly, flow control module  40  includes a flow control member  80  that selectively, passively, extends into flow passage  47  during off-peak operation such as shown in  FIG. 4 . The term passively should be understood to mean that flow control member  80  extends into flow passage  47  based on a parameter of the air flow, not as a result of a particular control input. In accordance with the exemplary embodiment shown, flow control member  80  includes a bi-metallic element  86  embedded in first side wall  53 . Bi-metallic element  86  includes a first member  90  that is joined to a second member  91 . 
         [0019]    When exposed to particular temperature ranges, first and second members  90  and  91  expand and contract relative to one another. In the present case, when exposed to air flow during peak or near peak operation, first and second members  90  and  91  conform to curvilinear surface portion  59  such as shown in  FIG. 3 . However, when exposed to air flow during off-peak operations, first member  90  contracts at a rate that is distinct from a rate of contraction of second member  91  resulting in flow control member  80  bulging or extending into flow passage  47  such as shown in  FIG. 4 . In this manner, flow control member  80  reduces an overall air flow passing to wheel space  34 . The reduction in air flow passing into wheel space  34  leads to an increase in compressor flow passing to combustor assembly  20 . The increase in compressor flow to combustor assembly  20  leads to more complete combustion at off-peak operation so as to reduce emissions and increase efficiency. 
         [0020]    Reference will now be made to  FIG. 5  in describing a flow control module  140  in accordance with another aspect of the exemplary embodiment. Flow control module  140  includes an inlet  144  that leads to an outlet  145  through a flow passage  147 . Flow passage  147  includes first and second opposing side walls  153  and  154  that are joined by a third side wall  156  and a fourth side wall (not shown). First side wall  153  includes a curvilinear surface portion  159 . Similarly, second side wall  154  includes a curvilinear surface portion  160 . Third side wall  156  includes a substantially linear or smooth surface  162 . Similarly, the fourth side wall (not shown) likewise includes a substantially linear or smooth surface (also not shown). In a manner similar to that described above, curvilinear surface portions  159  and  160  are shaped so as to guide the cooling flow from diffuser  30  into wheel space  34  at an angle. 
         [0021]    Flow control module  140  includes a flow control member  180  that selectively, passively, extends into flow passage  147  during off-peak operation. In accordance with the exemplary aspect shown, flow control member  180  includes a bi-metallic element  186  embedded in third side wall  156 . More specifically, flow control member  180  extends across or spans flow passage  147  and connects with first and second side walls  153  and  154 . Bi-metallic element  186  includes a first member  190  that is joined to a second member (not shown). In a manner similar to that described above, bi-metallic element extends into flow passage  147  during off-peak operation in order to reduce air flow passing into wheel space  34  and increase compressor flow passing to combustor assembly  20  to enhance combustion and reduce emissions. 
         [0022]    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.