Gas turbine engine tip clearance control

Abstract

A gas turbine engine is disclosed having a thermoelectric device capable of changing a tip clearance in a turbomachinery component. In one non-limiting form the turbomachinery component is a compressor. The thermoelectric device can be used in some forms to harvest power derived from a waste heat. The tip clearance control system can include a sensor used to determine a clearance between a tip and a wall of the turbomachinery component.

What is claimed is: 
     
         1 . An apparatus comprising:
 a gas turbine engine flow path wall forming a boundary for the flow of a working fluid through a turbomachinery component having an airfoil shaped component during operation of a gas turbine engine;   a thermoelectric device in thermal communication with the gas turbine engine flow path wall; and   a control module structured to regulate the thermoelectric device to influence a thermally induced gap between the gas turbine engine flow path wall and the airfoil shaped component.   
     
     
         2 . The apparatus of  claim 1 , wherein the control module can regulate the thermoelectric device to selectively heat the gas turbine engine flow path wall in a first mode of operation and selectively cool the gas turbine engine flow path wall in a second mode of operation. 
     
     
         3 . The apparatus of  claim 1 , wherein the thermoelectric device is in thermal communication with protrusions that project into a cooling space. 
     
     
         4 . The apparatus of  claim 1 , wherein the control module regulates the thermoelectric device on basis of a sensed clearance derived from a proximity sensor. 
     
     
         5 . The apparatus of  claim 4 , wherein the proximity sensor operates according to one of capacitive principles and optical principles. 
     
     
         6 . The apparatus of  claim 1 , wherein in a first mode of operation the thermoelectric device is used to generate a potential difference based upon a waste heat of the gas turbine engine. 
     
     
         7 . The apparatus of  claim 1 , wherein the thermoelectric device includes a plurality of P-Type and N-Type semiconductors. 
     
     
         8 . The apparatus of  claim 7 , wherein a first P-Type semiconductor and a first N-Type semiconductors are located at different flow stream locations, wherein the plurality of semiconductors extend around the full circumference of the gas turbine engine flow path wall, and wherein a thermally conductive bond is used to coupled the thermoelectric device with the turbomachinery component. 
     
     
         9 . An apparatus comprising:
 a gas turbine engine flow component having a flow path defined by a wall and in which is disposed a blade used to alter a direction of a flow through the component; and   a tip clearance control system configured to change a distance between the wall and the blade, the clearance control system having an electrical device that includes a junction between dissimilar materials in thermal communication with the wall wherein a potential difference across the junction is related to a temperature difference across the junction.   
     
     
         10 . The apparatus of  claim 9 , wherein the tip clearance control system is structured to regulate a voltage across the electrical device to perform one of heating the gas turbine engine flow component and cooling the gas turbine engine flow component. 
     
     
         11 . The apparatus of  claim 9 , which further includes a sensor in feedback relation with the tip clearance control system, the sensor operable to provide a regulation variable such that the distance between the wall and the rotatable blade is controlled. 
     
     
         12 . The apparatus of  claim 11 , wherein the sensor generates a signal representative of a distance between the wall and at least one of the blades. 
     
     
         13 . The apparatus of  claim 9 , wherein the proximity sensor includes one of a capacitor and an optical sensor. 
     
     
         14 . The apparatus of  claim 9 , wherein during operation of the tip clearance control system, waste heat from the gas turbine engine is used to power the thermoelectric device. 
     
     
         15 . The apparatus of  claim 9 , which further includes an energy storage device to harvest potential difference generated by the waste heat. 
     
     
         16 . An apparatus comprising:
 a gas turbine engine having rotatable blade and an end wall; and   means for thermoelectrically changing a distance between the blade and the end wall.   
     
     
         17 . A method comprising:
 operating a gas turbine engine to produce a flow stream through a turbomachinery component of the gas turbine engine;   moving a bladed row of airflow members in the turbomachinery component, the flow stream traversing through the bladed row;   flowing an electrical current across a junction of two dissimilar materials to produce a heating response;   changing a clearance between a wall and the tips of the bladed row in proximity with the wall.   
     
     
         18 . The method of  claim 17 , wherein the flowing occurs as a result of a thermoelectric phenomena, and the flowing results in a cooling of a wall member of the turbomachinery component. 
     
     
         19 . The method of  claim 18 , which further includes changing a tip clearance of the turbomachinery component. 
     
     
         20 . The method of  claim 19 , which further includes determining a tip clearance to aid in the changing a tip clearance. 
     
     
         21 . The method of  claim 20 , wherein the determining includes sensing the tip clearance with a sensor that operates according to one of capacitive or optical principles.