Passive flow modulation of cooling flow into a cavity

Abstract

A passive flow modulation device according to an embodiment includes: a temperature sensitive element disposed within a first area; a piston coupled to the temperature sensitive element, the piston extending through a wall to a second area, wherein the first area is at a higher temperature than the second area; and a valve arrangement disposed in the second area and actuated by a distal end portion of the piston, the valve arrangement tangentially injecting a supply of cooling air through an angled orifice from the second area into the first area in response an increase in temperature in the first area.

What is claimed is: 
     
         1 . A passive flow modulation device, comprising:
 a temperature sensitive element disposed within a first area;   a piston coupled to the temperature sensitive element, the piston extending through a wall to a second area, wherein the first area is at a higher temperature than the second area; and   a valve arrangement disposed in the second area and actuated by a distal end portion of the piston, the valve arrangement tangentially injecting a supply of cooling air through an angled orifice from the second area into the first area in response an increase in temperature in the first area.   
     
     
         2 . The passive flow modulation device according to  claim 1 , wherein the first area and the second area are located within a turbine. 
     
     
         3 . The passive flow modulation device according to  claim 2 , wherein the first area is disposed between a stator and rotor of the turbine. 
     
     
         4 . The passive flow modulation device according to  claim 2 , wherein the angled orifice further comprises a pre-swirl orifice or a flow inducer. 
     
     
         5 . The passive flow modulation device according to  claim 2 , wherein the first area comprises a wheelspace cavity of the turbine. 
     
     
         6 . The passive flow modulation device according to  claim 1 , wherein the first area contains a rotating flow of air, and wherein the supply of cooling air is injected into the first area through the angled orifice in a direction of rotation of the rotating flow of air. 
     
     
         7 . The passive flow modulation device according to  claim 1 , wherein the supply of cooling air injected into the first area increases in response to a further increase in the temperature in the first area. 
     
     
         8 . The passive flow modulation device according to  claim 1 , wherein the temperature sensitive element comprises a housing containing a thermally expandable material. 
     
     
         9 . A passive flow modulation device, comprising:
 a temperature sensitive element;   a piston coupled to the temperature sensitive element, the piston including a head section, wherein the temperature sensitive element and the piston are disposed in a first area; and   an orifice, extending from a second area into the first area, for supplying a flow of cooling air from the second area to the first area, wherein the first area is at a higher temperature than the second area;   wherein the temperature sensitive element enlarges or contracts to selectively position the head of the piston over a portion of the aperture to control the flow of cooling air from the second area into the first area.   
     
     
         10 . The passive flow modulation device according to  claim 9 , wherein the orifice comprises an angled orifice, and wherein a distal end of the head of the piston includes an angled surface. 
     
     
         11 . The passive flow modulation device according to  claim 10 , wherein the angled surface of the head of the piston has a shape corresponding to a flow angle of the cooling air through the angled orifice. 
     
     
         12 . The passive flow modulation device according to  claim 9 , wherein the first area and the second area are located within a turbine. 
     
     
         13 . The passive flow modulation device according to  claim 12 , wherein the first area comprises a wheelspace cavity of the turbine. 
     
     
         14 . The passive flow modulation device according to  claim 9 , wherein the orifice comprises a pre-swirl orifice or a flow inducer. 
     
     
         15 . The passive flow modulation device according to  claim 9 , wherein the first area contains a rotating flow of air, and wherein the flow of cooling air is injected into the first area through the angled orifice in a direction of rotation of the rotating flow of air. 
     
     
         16 . The passive flow modulation device according to  claim 9 , wherein the temperature sensitive element comprises a housing containing a thermally expandable material. 
     
     
         17 . A cooling system for a turbine, comprising:
 an orifice located between a first area and a second area of the turbine, wherein the first area of the turbine is at a higher temperature than the second area of the turbine;   a passive flow modulation device disposed adjacent the orifice for directing a flow of cooling air through the orifice from the second area of the turbine to the first area of the turbine, the passive flow modulation device including:
 a temperature sensitive element disposed within the first area; 
 a piston coupled to the temperature sensitive element, the piston extending through a wall to the second area; and 
 a valve arrangement disposed in the second area and actuated by a distal end portion of the piston, the valve arrangement selectively directing the flow of cooling air through the orifice from the second area into the first area in response a change in temperature in the first area; or 
 a temperature sensitive element; and 
 a piston coupled to the temperature sensitive element, the piston including a head section, wherein the temperature sensitive element and the piston are disposed in the first area; 
 wherein the temperature sensitive element enlarges or contracts in response to a change in temperature in the first area to selectively position the head of the piston over a portion of the aperture to control the flow of cooling air from the second area into the first area. 
   
     
     
         18 . The cooling system according to  claim 17 , wherein the orifice comprise an angled orifice, and wherein the angled orifice comprises a pre-swirl orifice or a flow inducer. 
     
     
         19 . The cooling system according to  claim 17 , wherein the first area comprises a wheelspace cavity of the turbine. 
     
     
         20 . The cooling system according to  claim 17 , wherein the first area contains a rotating flow of air, and wherein the flow of cooling air is directed from the second area into the first area through the orifice in a direction of rotation of the rotating flow of air.