Systems and Methods for Providing a Flow of Purge Air and an Adjustable Flow of Cooling Air in a Gas Turbine Application

Abstract

Embodiments of the disclosure include systems and methods for providing a flow of purge air and an adjustable flow of cooling air to a wheel space cavity or a stator cavity. According to one embodiment, there is disclosed a turbine assembly. The turbine assembly may include a rotor assembly, a stator assembly positioned adjacent to the rotor assembly, and a wheel space cavity formed between the rotor assembly and the stator assembly. At least one fixed purge air orifice may be associated with the stator assembly. The fixed purge air orifice may be configured to provide a flow of purge air to the wheel space cavity. Moreover, at least one adjustable cooling air orifice may be associated with the stator assembly. The at least one adjustable cooling air orifice may be configured to provide a flow of cooling air to the wheel space cavity.

That which is claimed: 
     
         1 . A turbine assembly, comprising:
 a rotor assembly;   a stator assembly positioned adjacent to the rotor assembly;   a wheel space cavity formed between the rotor assembly and the stator assembly;   at least one fixed purge air orifice associated with the stator assembly; and   at least one adjustable cooling air orifice associated with the stator assembly, wherein the at least one fixed purge air orifice is configured to provide a flow of purge air to the wheel space cavity, and wherein the at least one adjustable cooling air orifice is configured to provide an adjustable flow of cooling air to the wheel space cavity.   
     
     
         2 . The assembly of  claim 1 , further comprising a flow control device associated with the at least one adjustable cooling air orifice, wherein the flow control device is configured to vary the flow of cooling air to the wheel space cavity by varying the size of the at least one adjustable cooling air orifice. 
     
     
         3 . The assembly of  claim 2 , wherein the stator assembly comprises:
 a stator wall; and   a stator cavity defined by the stator wall, wherein the stator cavity is in communication with a flow of compressor extraction air.   
     
     
         4 . The assembly of  claim 3 , wherein the at least one fixed purge air orifice is positioned in the stator wall. 
     
     
         5 . The assembly of  claim 3 , wherein the at least one adjustable cooling air orifice is positioned in the stator wall. 
     
     
         6 . The assembly of  claim 3 , wherein the flow control device is positioned within the stator cavity. 
     
     
         7 . The assembly of  claim 3 , wherein the flow of compressor extraction air forms at least a portion of the flow of purge air and the flow of cooling air. 
     
     
         8 . The assembly of  claim 1 , further comprising a temperature sensor associated with the wheel space cavity and in communication with the at least one adjustable cooling air orifice. 
     
     
         9 . The assembly of  claim 1 , further comprising an inter-stage seal positioned between the rotor assembly and the stator assembly. 
     
     
         10 . A turbine assembly, comprising:
 a rotor assembly;   a stator assembly positioned adjacent to the rotor assembly;   a wheel space cavity formed between the rotor assembly and the stator assembly;   at least one purge air circuit associated with the stator assembly; and   at least one cooling air circuit associated with the stator assembly, wherein the at least one purge air circuit is configured to provide a flow of purge air to the wheel space cavity, and wherein the at least one cooling air circuit is configured to provide an adjustable flow of cooling air to the wheel space cavity.   
     
     
         11 . The assembly of  claim 10 , further comprising a flow control device associated with the at least one cooling air circuit, wherein the flow control device is configured to vary the flow of cooling air to the wheel space cavity. 
     
     
         12 . The assembly of  claim 11 , wherein the flow control device comprises a valve in communication with the at least one cooling air circuit. 
     
     
         13 . The assembly of  claim 10 , wherein the stator assembly comprises:
 a stator wall; and   a stator cavity defined by the stator wall, wherein the stator cavity is in communication with a flow of compressor extraction air.   
     
     
         14 . The assembly of  claim 13 , wherein the at least one purge air circuit comprises an orifice positioned in the stator wall. 
     
     
         15 . The assembly of  claim 14 , wherein the orifice is fixed 
     
     
         16 . The assembly of  claim 13 , wherein the at least one cooling air circuit comprises an adjustable orifice positioned in the stator wall. 
     
     
         17 . The assembly of  claim 10 , further comprising a temperature sensor associated with the wheel space cavity and in communication with the at least one cooling air circuit. 
     
     
         18 . The assembly of  claim 10 , further comprising an inter-stage seal positioned between the rotor assembly and the stator assembly. 
     
     
         19 . A method for providing a flow of purge air and a flow of cooling air to a cavity in a gas turbine assembly, comprising:
 providing the flow purge air to the cavity by way of at least one fixed purge air orifice; and   varying the flow of cooling air to the cavity by way of at least one adjustable cooling air orifice, wherein the cavity comprises a wheel space cavity or a stator cavity.   
     
     
         20 . The method of  claim 19 , further comprising varying the size of the at least one adjustable cooling air orifice with a flow control device. 
     
     
         21 . A system for providing an adjustable flow of cooling air from a stator cavity to a wheel space cavity of a turbine assembly, the system comprising:
 at least one cooling air passage configured to provide the adjustable flow of cooling air to the wheel space cavity from the stator cavity; and   a flow control device associated with the at least one cooling air passage, the flow control device comprising:
 a valve configured to control the adjustable flow of cooling air within the at least one cooling air passage; and 
 a temperature dependent actuator positioned at least partially within the wheel space cavity and in mechanical communication with the valve, wherein the temperature dependent actuator is configured to open and close the valve. 
   
     
     
         22 . The system of  claim 21 , wherein the temperature dependent actuator comprises:
 an actuator housing positioned at least partially within the wheel space cavity; and   a temperature dependent element positioned within the actuator housing, wherein the temperature dependent element is configured to expand or contract in response to a temperature of the wheel space cavity to open and close the valve.   
     
     
         23 . The system of  claim 21 , wherein the valve comprises:
 a valve body in fluid communication with the at least one cooling air passage; and   a valve disc configured to open and close in response to the temperature dependent actuator to modulate the adjustable flow of cooling air provided to the wheel space cavity by the at least one cooling air passage.   
     
     
         24 . The system of  claim 21 , wherein the at least one cooling air passage is positioned upstream of the temperature dependent actuator so as to deliver the adjustable flow of cooling air upstream of the temperature dependent actuator. 
     
     
         25 . The system of  claim 21 , further comprising at least one fixed purge air orifice in communication with the wheel space cavity, wherein the at least one fixed purge air orifice is configured to provide a constant flow of purge air to the wheel space cavity.