Measuring rotor imbalance via blade clearance sensors

Abstract

A system and method can be utilized to determine an out of balance condition of a rotor having a plurality of blades. The system monitors a clearance between the blades and an associated housing. By looking at a center of that clearance information, a determination can be made of the magnitude of imbalance of the rotor.

1 . A system for identifying an out of balance rotor comprising:
 a sensor for sensing a clearance between a plurality of blades and a housing surface, clearance information from said sensor being delivered to a control; and   said control being operable to receive said clearance information, and determine a center of the clearance information, and compare the distance between an actual center of the clearance information, and an expected center of the clearance information should there be no imbalance, said distance being taken as a magnitude of imbalance of the rotor.   
     
     
         2 . The system as set forth in  claim 1 , wherein said sensor sends a microwave signal, and receives and analyzes a reflected microwave signal. 
     
     
         3 . The system as set forth in  claim 1 , wherein a plurality of revolutions of the rotor are taken as said clearance information. 
     
     
         4 . The system as set forth in  claim 1 , wherein said rotor imbalance is determined in real time. 
     
     
         5 . The system as set forth in  claim 1 , wherein the location of the actual center of the clearance information is used to determine the location of the imbalance. 
     
     
         6 . The system as set forth in  claim 1 , wherein said system is mounted on a gas turbine engine. 
     
     
         7 . A method for identifying an out of balance rotor comprising:
 gathering clearance information of the clearance between a plurality of blades and a housing surface; and   determining a center of the clearance information, and comparing a distance between an actual center of the clearance information, and an expected center of the clearance information should there be no imbalance, said distance being taken as a magnitude of imbalance of the rotor.   
     
     
         8 . The method as set forth in  claim 7 , wherein said sensor sends a microwave signal, and receives and analyzes a reflected microwave signal. 
     
     
         9 . The method as set forth in  claim 7 , wherein a plurality of revolutions of the rotor are taken as said clearance information. 
     
     
         10 . The method as set forth in  claim 7 , wherein said rotor imbalance is determined in real time. 
     
     
         11 . The method as set forth in  claim 7 , wherein the location of the actual center of the clearance information is used to determine the location of the imbalance. 
     
     
         12 . A gas turbine engine comprising:
 at least one rotor having a plurality of blades, the blades rotating spaced from a housing surface;   a sensor for sensing a clearance between the plurality of blades and the housing surface, clearance information from said sensor being delivered to a control; and   said control being operable to receive said clearance information, and determine a center of the clearance information, and compare the distance between an actual center of the clearance information, and an expected center of the clearance information should there be no imbalance, said distance being taken as a magnitude of imbalance of the rotor.   
     
     
         13 . The engine as set forth in  claim 12 , wherein said sensor sends a microwave signal, and receives and analyzes a reflected microwave signal. 
     
     
         14 . The engine as set forth in  claim 12 , wherein a plurality of revolutions of the rotor are taken as said clearance information. 
     
     
         15 . The engine as set forth in  claim 12 , wherein said rotor imbalance determination is determined in real time. 
     
     
         16 . The engine as set forth in  claim 12 , wherein the location of the actual center of the clearance information is used to determine the location of the imbalance.