Tip shroud monitoring system, method, and controller

Abstract

A tip shroud of a bladed rotor can be monitored for integrity using a sensor configured to detect the tip shroud. A signal from the sensor can be monitored and if the magnitude of the signal changes, such as beyond a defined amount, an indication of possible damage can be made. A baseline sensed pattern for a revolution of the tip shroud can be compared to an operation sensed pattern for a subsequent revolution, and the indication of damage can be made if there is more than the defined amount and/or percentage of difference between the patterns.

What is claimed is: 
     
         1 . A monitoring system for a tip shroud of a rotor, the system comprising:
 a sensor responsive to the tip shroud; and   a control system configured to perform the following:
 receive a signal from the sensor; 
 monitor the signal from the sensor; 
 compare a value of a characteristic of the signal to a reference value of the characteristic; and 
 indicate possible tip shroud damage responsive to an amount of change in the value of the characteristic of the signal exceeding a defined amount of allowable change. 
   
     
     
         2 . The monitoring system of  claim 1 , wherein the reference value includes a previously received value of the characteristic. 
     
     
         3 . The monitoring system of  claim 1 , wherein the control system is further configured to determine a baseline sensed pattern using the signal, the reference value includes the baseline sensed pattern, comparing the value of the characteristic of the signal to the reference value includes comparing the value to the baseline sensed pattern, and the control system is further configured to determine the amount of change between the value and the baseline sensed pattern. 
     
     
         4 . The monitoring system of  claim 3 , wherein the control system is further configured to perform the following:
 determine, as part of monitoring the signal from the sensor, an operation sensed pattern using the signal from the sensor;   determine, as part of comparing the signal to the reference value, an amount of change between corresponding portions of the operation sensed pattern and the baseline sensed pattern; and   indicate possible tip shroud damage responsive to an amount of change exceeding the defined amount.   
     
     
         5 . The monitoring system of  claim 4 , wherein the baseline sensed pattern is an immediately previous operation sensed pattern. 
     
     
         6 . The monitoring system of  claim 4 , wherein, to determine the baseline sensed pattern, the control system is further configured store a first series of values of the characteristic of the respective signal during a revolution of the tip shroud, and to determine the operation sensed pattern, the control system is further configured to store a second series of values of the characteristic of the signal during a subsequent revolution of the tip shroud, each of the second series of values corresponding to a respective one of the first series of values. 
     
     
         7 . A method for monitoring a tip shroud of a rotor, the method comprising:
 receiving a signal indicative of a presence of the tip shroud;   monitoring a value of a characteristic of the signal;   determining an amount of change in the value of a characteristic of the signal;   comparing the amount of change to a defined amount of allowable change; and   indicating possible damage to the tip shroud responsive to the amount of change exceeding a defined amount of allowable change.   
     
     
         8 . The method of  claim 7 , wherein the monitoring of the value includes determining a baseline sensed pattern of the value for a revolution of an undamaged tip shroud, and the determining of an amount of change includes comparing the monitored value to a corresponding portion of the baseline sensed pattern. 
     
     
         9 . The method of  claim 8 , wherein:
 the monitoring of the value includes determining an operation sensed pattern of the value of the characteristic of the signal during a subsequent revolution of the tip shroud; and   the determining of an amount of change further includes determining a change between corresponding portions of the baseline sensed pattern and the operation sensed pattern, wherein the indicating of possible damage is responsive to the amount of change between corresponding values exceeding the defined amount.   
     
     
         10 . The method of  claim 9 , further comprising replacing the baseline sensed pattern with the operation sensed pattern, repeating the determining an operation sensed pattern for another revolution of the tip shroud, repeating the determining an amount of change between corresponding portions of the baseline sensed pattern and the operation sensed pattern, and repeating the indicating possible tip shroud damage responsive to the amount of change between corresponding portions exceeding the defined amount. 
     
     
         11 . The method of  claim 9 , wherein determining a baseline sensed pattern includes storing a first series of values of the monitored characteristic for the revolution of the tip shroud, the determining of the operation sensed pattern includes storing a second series of values of the monitored characteristic or the subsequent revolution of the tip shroud, each of the second series of values corresponding to a respective one of the first series of values. 
     
     
         12 . The method of  claim 7 , further comprising determining the defined amount using at least one of manufacturing tolerances of the tip shroud, a characteristic of an environment in which the tip shroud operates, or deflection of at least one component of the tip shroud. 
     
     
         13 . In a machine including a rotor mounted for rotation relative to another part of the machine, the rotor including a tip shroud, a tip shroud monitoring controller configured for:
 receiving a signal from a sensor configured to detect the tip shroud;   monitoring the signal;   comparing a value of a characteristic of the signal to a reference value;   determining a difference between the value and the reference value; and   indicating possible tip shroud damage responsive to the difference exceeding a defined amount.   
     
     
         14 . The controller of  claim 13 , wherein the reference value includes a previous value of the characteristic, the difference represents an amount of change in value of the characteristic, and the indicating of possible tip shroud damage is responsive to the amount of change exceeding a defined amount. 
     
     
         15 . The controller of  claim 13 , wherein the monitoring of the signal further comprises determining a baseline sensed pattern of the monitored signal for a revolution of the tip shroud, the reference value includes the baseline sensed pattern, and the comparing of the value to the reference value includes comparing the value to a corresponding portion of the baseline sensed pattern. 
     
     
         16 . The controller of  claim 15 , wherein the monitoring of the signal further comprises determining an operation sensed pattern of the monitored signal for a subsequent revolution of the tip shroud, and the comparing of the value to the reference value includes comparing corresponding portions of the baseline and operation sensed patterns. 
     
     
         17 . The controller of  claim 16 , wherein the determining of the baseline sensed pattern includes storing a previous operation sensed pattern. 
     
     
         18 . The controller of  claim 16 , further configured for replacing the baseline sensed pattern with the operation sensed pattern, the operation sensed pattern becoming the baseline sensed pattern, repeat determining an operation sensed pattern for another revolution of the tip shroud, repeating determining an amount of change between corresponding portions of the baseline and operation sensed patterns, and indicating possible tip shroud damage responsive to an amount of change exceeding the defined amount. 
     
     
         19 . The controller of  claim 16 , wherein the determining of the baseline sensed pattern includes storing a first series of values of the characteristic of the monitored signal for the revolution of the tip shroud, the determining of the operation sensed pattern includes storing a second series of values of the characteristic of the monitored signal for the subsequent revolution of the tip shroud, each of the second series of values corresponding to a respective one of the first series of values, and the comparing of the value to the reference value includes comparing corresponding values of the first and second series of values. 
     
     
         20 . The controller of  claim 13 , further comprising determining the defined amount, including taking into account at least one of a manufacturing variation or an operating condition of the tip shroud.