System and methods for determining blade clearance for asymmertic rotors

Patent metadata

Field	Value
Publication number	US-2016319695-A1
Application number	US-201415109055-A
Country	US
Kind code	A1
Filing date	Dec 19, 2014
Priority date	Dec 31, 2013
Publication date	Nov 3, 2016
Grant date	—

Abstract

A system and methods are provided for determining blade clearance for asymmetrical rotors. In one embodiment, a method includes detecting displacement data of a rotor blade coupled to a shaft, receiving tachometer data determined for rotation speed of the shaft, and resampling the displacement data of the rotor blade based on the tachometer data. Resampling may include sampling the displacement data at constant increments of shaft rotation. The method may also include determining blade clearance based on the resampled displacement data.

First claim

What is claimed is:

1 . A method for determining blade clearance for asymmetrical rotors, the method comprising the acts of:
detecting displacement data of a rotor blade coupled to a shaft; receiving tachometer data determined for rotation speed of the shaft; resampling the displacement data of the rotor blade based on the tachometer data, wherein resampling includes sampling the displacement data at constant increments of shaft rotation; and determining blade clearance based on the resampled displacement data.

2 . The method of claim 1 , wherein the displacement data for the rotor blade includes blade length measurement data.

3 . The method of claim 1 , wherein displacement data for the rotor blade is instantaneous displacement data of the rotor blade determined by a capacitive sensor.

4 . The method of claim 1 , wherein the tachometer data is determined by a tachometer producing pulses at regular intervals.

5 . The method of claim 1 , wherein angular resampling generates a resampled waveform for each revolution of the rotor blade based on
determining zero up-crossings for the tachometer data, determining an angle of shaft of interest at each up-crossing, interpolating up-crossing angles to find shaft angle at all original sample times, and interpolating the signal at equal angular increments.

6 . The method of claim 1 , further comprising computing a moving synchronous average to produce a time domain representation of the displacement signal over one shaft rotation for each rotation.

7 . The method of claim 6 , wherein computing the moving synchronous average includes determining one or more of a standard deviation and peak-to-peak displacement of the moving synchronous average as an indication of blade clearance.

8 . The method of claim 7 , wherein the moving synchronous average is determined as a scalar feature which is sensitive to mean tip clearance.

9 . The method of claim 8 , further comprising computing temperature compensation of the scalar feature to compensate for thermal sensitivity of the sensor.

10 . The method of claim 1 , wherein displacement data for the rotor blade is output for control of a gas turbine engine.

11 . A system for determining blade clearance for asymmetrical rotors comprising:
a displacement sensor configured to detect displacement data of a rotor blade coupled to a shaft; a tachometer configured to output tachometer data for rotation speed of the shaft; an analysis unit coupled to the displacement sensor and tachometer, the analysis unit configured to
resample the displacement data of the rotor blade based on the tachometer data, wherein resampling includes sampling the displacement data at constant increments of shaft rotation; and
output an indication of blade clearance based on the resampled displacement data.

12 . The system of claim 11 , wherein the displacement data for the rotor blade includes blade length measurement data.

13 . The system of claim 11 , wherein displacement data for the rotor blade is instantaneous displacement data of the rotor blade determined by a capacitive sensor.

14 . The system of claim 11 , wherein the tachometer produces pulses at regular intervals.

15 . The system of claim 11 , wherein angular resampling generates a resampled waveform for each revolution of the rotor blade based on the analysis unit
determining zero up-crossings for the tachometer data, determining an angle of shaft of interference at each up-crossing, interpolating up-crossing angles to find shaft angle at all original sample times, and interpolating the signal at equal angular increments.

16 . The system of claim 11 , further comprising computing a moving synchronous average to produce a time domain representation of the displacement signal over one shaft rotation for each rotation.

17 . The system of claim 16 , wherein computing the moving synchronous average includes determining one or more of a standard deviation and peak-to-peak displacement of the moving synchronous average as an indication of blade clearance.

18 . The system of claim 17 , wherein computing the moving synchronous average is determined as a scalar feature which is sensitive to mean tip clearance.

19 . The system of claim 18 , further comprising computing temperature compensation of the scalar feature to compensate for thermal sensitivity of the sensor.

20 . The system of claim 11 , wherein displacement data for the rotor blade is output for control of a gas turbine engine.

Assignees

• Isom Joshua D
• Pawelcik Clifford
• Hockaday Bruce
• United Technologies Corp

Inventors

• Isom Joshua D
• Pawelcik Clifford
• Hockaday Bruce

Classifications

• F01D21/003 Primary

  Arrangements for testing or measuring (for measuring vibrations G01H) · CPC title

• G01B21/16

  for measuring distance of clearance between spaced objects · CPC title

• F01D11/20

  Actively adjusting tip-clearance · CPC title

• F01D5/12

  Blades ({specially adapted for radial flow machines or engines F01D5/04}; blade roots F01D5/30; rotors with blades adjustable in operation F01D7/00; stator blades F01D9/02) · CPC title

• G01B7/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B7/30 takes precedence) · CPC title