Part load performance improvement using deformable boreplugs

Abstract

A cooling arrangement for a gas turbine engine includes a discharge channel for airflow from a compressor, a first cooling channel, and at least one aperture providing communication between the flow of air through the discharge channel and the first cooling channel. A restrictor device in the aperture regulates the flow of air between the discharge channel and the first cooling channel. The restrictor device deforms to vary air flowing through the aperture in response to a physical condition of the engine. This physical condition of the engine may be that of the temperature of air flowing through the discharge channel or the power output of the gas turbine engine. The restrictor device may be a boreplug, which may be a two-way shape memory alloy.

What is claimed is: 
     
         1 . A cooling arrangement for a gas turbine engine, comprising:
 a discharge channel for airflow from a compressor;   a first cooling channel;   a compressor discharge case forming a boundary between the discharge channel and the first cooling channel;   at least one aperture through the compressor discharge case providing communication for flow of air between the discharge channel and the first cooling channel; and   at least one boreplug positioned within the aperture that regulates the flow of air between the discharge channel and the first cooling channel through the aperture in response to a physical condition of the gas turbine engine;   wherein the boreplug deforms in response to the physical condition, thereby regulating airflow through the at least one aperture; and   wherein the physical condition is selected from the group consisting of a temperature of discharge air flowing through the discharge channel, a power output of the gas turbine engine, and a combination thereof.   
     
     
         2 . The cooling arrangement of  claim 1 , wherein the boreplug is a shape memory alloy. 
     
     
         3 . The cooling arrangement of  claim 2 , wherein the shape memory alloy is a two-way shape memory alloy. 
     
     
         4 . The cooling arrangement of  claim 3 , wherein the two-way shape memory alloy has the formula (A 1-x PGM x ) 0.5+y B 0.5−y  wherein PGM is a platinum group metal selected from the group consisting of Pt, Pd, Rh, Ru, Ir, and combinations thereof. 
     
     
         5 . The two-way shape memory alloy of  claim 4  having the formula (A 1-x PGM x ) 0.5+y B 0.5−y , wherein A is selected from the group consisting of Ni, Al, Nb, Ti, Ta, and combinations thereof. 
     
     
         6 . The two-way shape memory alloy of  claim 5  having the formula (A 1-x PGM x ) 0.5+y B 0.5−y  wherein B is selected from the group consisting of Al, Cr, Hf, Zr, La, Y, Ce, Ti, Mo, W, Nb, Re, Ta, V, and combinations thereof. 
     
     
         7 . The cooling arrangement of  claim 2 , wherein the shape memory alloy is responsive to a temperature experienced by the gas turbine engine. 
     
     
         8 . The cooling arrangement of  claim 1 , wherein the at least one aperture comprises a plurality of apertures providing communication between the discharge channel and the first cooling channel. 
     
     
         9 . The cooling arrangement of  claim 8 , wherein the at least one boreplug comprises a plurality of boreplugs, the boreplugs being positioned in at least some of the plurality of apertures. 
     
     
         10 . The cooling arrangement of  claim 9 , wherein the boreplugs are shape memory alloys. 
     
     
         11 . The cooling arrangement of  claim 10 , wherein the shape memory alloys are two-way shape memory alloys having the formula (A 1-x PGM x ) 0.5+y B 0.5−y , wherein PGM is a platinum group metal selected from the group consisting of Pt, Pd, Rh, Ru, Ir, and combinations thereof. 
     
     
         12 . The two-way shape memory alloys of  claim 11  having the formula (A 1-x PGM x ) 0.5+y B 0.5−y , wherein A is selected from the group consisting of Ni, Al, Nb, Ti, Ta, and combinations thereof. 
     
     
         13 . The two-way shape memory alloys of  claim 12  having the formula (A 1-x PGM x ) 0.5+y B 0.5−y , wherein B is selected from the group consisting of Al, Cr, Hf, Zr, La, Y, Ce, Ti, Mo, W, Nb, Re, Ta, V, and combinations thereof. 
     
     
         14 . The cooling arrangement of  claim 11 , wherein:
 when the temperature of airflow of the discharge air is below a first preselected temperature for the boreplug, each of the two-way shape memory alloys assumes a first shape such that the boreplug is in a closed state and little or no air flows through the aperture; and   when the temperature of airflow of the discharge air reaches the first preselected temperature for the boreplug, each of the two-way shape memory alloys assume a second shape such that the boreplug is in an open state to allow air to flow freely through the aperture such that airflow is regulated by the temperature of the discharge air.   
     
     
         15 . The cooling arrangement of  claim 10 , wherein:
 the boreplugs comprise a first portion of boreplugs of a first two-way shape memory alloy and a second portion of boreplugs of a second two-way shape memory alloy;   when the temperature of airflow of the discharge air is below a first preselected temperature, each of the first two-way shape memory alloys assumes a first shape such that the first portion of boreplugs is in a closed state and little or no air flows through the aperture;   when the temperature of airflow of the discharge air reaches the first preselected temperature, each of the first two-way shape memory alloys assumes a second shape such that the first portion of boreplugs is in an open state to allow air to flow freely through the aperture such that airflow is regulated by the temperature of the discharge air;   when the temperature of airflow of the discharge air is below a second preselected temperature, each of the second two-way shape memory alloys assumes a third shape such that the second portion of boreplugs is in a closed state and little or no air flows through the aperture;   when the temperature of airflow of the discharge air reaches the second preselected temperature, each of the second two-way shape memory alloys assumes a fourth shape such that the second portion of boreplugs is in an open state to allow air to flow freely through the aperture such that airflow is regulated by the temperature of the discharge air; and   the first preselected temperature and the second preselected temperature are different.   
     
     
         16 . The cooling arrangement of  claim 15 , wherein:
 the boreplugs comprise a third portion of boreplugs of a third two-way shape memory alloy;   when the temperature of airflow of the discharge air is below a third preselected temperature, each of the third two-way shape memory alloys assumes a fifth shape such that the third portion of boreplugs is in a closed state and little or no air flows through the aperture; and   when the temperature of airflow of the discharge air reaches the third preselected temperature, each of the third two-way shape memory alloys assumes a sixth shape such that the third portion of boreplugs is in an open state to allow air to flow freely through the aperture such that airflow is regulated by the temperature of the discharge air.   
     
     
         17 . The cooling arrangement of  claim 10 , wherein:
 each boreplug positioned in at least some of the plurality of apertures comprises a different shape memory alloy;   each shape memory alloy assumes a first shape such that each boreplug is closed when the temperature of airflow of the discharge air is below a first preselected temperature so that little or no air flows through the aperture;   each shape memory alloy assumes a second shape such that each boreplug is open to allow air to flow freely through the aperture when the temperature of airflow of the discharge air is at least at a second preselected temperature;   the first preselected temperature and the second preselected temperatures of each of the different shape memory alloys is different; and   the second preselected temperature is greater than the first preselected temperature for each of the different shape memory alloys;   whereby airflow from the discharge channel into the first cooling channel is modulated over a range of temperatures.   
     
     
         18 . The cooling arrangement of  claim 17 , wherein:
 each boreplug assumes the first shape and is closed when the temperature of airflow of the discharge air is below the first preselected temperature;   each boreplug assumes the second shape and is fully open when the boreplug is at least at the second preselected temperature; and   each boreplug assumes an intermediate shape between the first shape and the second shape when the temperature of airflow of the discharge air is between the first preselected temperature and the second preselected temperature.   
     
     
         19 . A gas turbine engine comprising:
 a combustor for combusting fuel with compressed air;   a turbine for generating power; and   a compressor for compressing air, the compressor comprising:
 a discharge channel for directing compressed air from the compressor downstream for combustor and cooling; 
 a cooling channel to provide cooling for cooling flow to turbine buckets; 
 a compressor discharge case forming a boundary between the cooling channel and the discharge channel; 
 at least one aperture in the compressor discharge case providing communication between airflow through the discharge channel and the first cooling channel; and 
 a restrictor device positioned in the aperture to regulate the airflow between the discharge channel and the cooling channel through the aperture in response to a physical condition of the gas turbine engine; 
   wherein the restrictor device deforms in response to at least one of a temperature of the airflow through the discharge channel and a power output of the gas turbine engine, thereby regulating the opening for airflow through the at least one aperture.   
     
     
         20 . The gas turbine engine of  claim 19 , wherein the restrictor device is a boreplug positioned in the aperture. 
     
     
         21 . The gas turbine engine of  claim 20 , wherein the boreplug is a shape memory alloy. 
     
     
         22 . The gas turbine engine of  claim 21 , wherein the shape memory alloy is a two-way shape memory alloy. 
     
     
         23 . The gas turbine engine of  claim 22 , wherein the two-way shape memory alloy has the formula (A 1-x PGM x ) 0.5+y B 0.5−y  wherein PGM is a platinum group metal selected from the group consisting of Pt, Pd, Rh, Ru, Ir and combinations thereof. 
     
     
         24 . The gas turbine engine of  claim 21 , wherein the shape memory alloy is responsive to an ambient temperature experienced by the gas turbine engine compressor inlet, wherein airflow temperature in the discharge channel from the compressor is directly related to the ambient temperature at the compressor inlet, wherein the shape memory alloy assumes a first shape when the shape memory alloy is in a martensitic state below a first temperature so as to substantially prevent airflow into the cooling channel, and wherein the shape memory alloy assumes a second shape when the shape memory alloy is in an austenitic state at or above the first temperature so as to substantially admit airflow into the cooling channel. 
     
     
         25 . The gas turbine engine of  claim 24 , wherein cross shank leakage across bucket shanks is reduced when the shape memory alloy is in the martensitic state below the first temperature, thereby preventing airflow into the cooling channel.