Patent Application
20130051976
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.
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.
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.
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.
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.
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.
These and other advantages and features will become more apparent from the following description taken in conjunction with 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:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
With reference to
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.
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
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
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
Reference will now be made to
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.
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.
