Turbine blade-mounted sensor fixture for tip gap measurement

摘要

Turbine blade tip clearance is measured in a fully assembled turbine casing by mounting a non-contact displacement probe or sensor on a turbine blade that generates data indicative of sensor distance from the turbine casing that circumferentially surrounds the blade. The sensor is mounted on the blade with a sensor fixture, which includes a clamping mechanism and a sensor retention mechanism that retains and calibrates the sensor by selective movement of the sensor relative to the retention mechanism. Variations in sensor distance data are recorded when the turbine is operated in turning gear mode. Blade rotational position data are collected by a rotational position sensor. A data processing system correlates the distance and rotational position data with localized blade tip gap at angular positions about the turbine casing circumference. This method and apparatus facilitate assessment of turbine casing deformation impact on blade tip clearance and rotor/casing alignment.

主权项

1. A method for measuring gas turbine blade tip and turbine casing radial clearance gap, comprising:
providing a gas turbine with a rotatable rotor having a turbine blade with a radially outwardly projecting tip in opposed spaced relationship with a circumscribing turbine casing, defining a gap there between; providing a non-contact displacement sensor that is capable of generating a displacement data set indicative of actual displacement; providing a sensor fixture including a sensor retention mechanism for calibrating the displacement sensor position and a clamp mechanism for clamping the fixture to the turbine blade; coupling the displacement sensor to the sensor fixture and coupling the sensor fixture to the turbine blade with the clamp mechanism, so that the non-contact displacement sensor is capable of generating a data set that is indicative of actual displacement relative to the circumscribing turbine casing without relative movement there between; calibrating the displacement sensor position relative to the blade tip by moving the entire displacement sensor within the sensor retention mechanism without moving the previously tightened clamping mechanism; coupling a rotor rotational position sensor to the turbine capable of determining actual rotational position without rotor rotational movement; rotating the rotor so that the turbine blade tip sweeps at least a portion of the circumscribing turbine casing while generating the displacement data set with the non-contact displacement sensor and a rotational position data set that is indicative of actual rotor rotational position with the rotational position sensor; acquiring the displacement and rotational position data sets from any rotor rotational starting position with a data acquisition system that is coupled to the displacement and rotational position sensors; and correlating blade tip and circumscribing turbine casing radial clearance gap relative to rotational position with the displacement and rotational data sets in a data analyzer system that is coupled to the data acquisition system.