EDGE DETECTOR

• US 20150132108A1
• Filed: 11/04/2014
• Published: 05/14/2015
• Est. Priority Date: 11/12/2013
• Status: Active Grant

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: JONES, Alan Richard
• Granted Patent: US 9,897,431 B2
• Time in Patent Office: Days
• US Class Current: 415/118
• CPC Class Codes: F01D 11/20 Actively adjusting tip-clearance
• CPC Class Codes: F01D 17/02 Arrangement of sensing elements
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01H 1/006 of the rotor of turbo machines

Abstract

An edge detector is provided for determining the axial position of the leading or trailing edge of a rotating blade within rotating machinery. The edge detector includes a set of axially spaced tip detection probes locatable within a casing of the machinery. Each probe is arranged to detect whether or not the blade tip passes over that probe. The edge detector determines the axial position of the edge of the blade as the position of the boundary between those tip detection probes which detect passage of the blade tip thereover and those tip detection probes which detect no passage of the blade tip thereover.

Claims

1. An edge detector for determining the axial position of the leading or trailing edge of a rotating blade within rotating machinery, the edge detector including:

a set of axially spaced tip detection probes locatable within a casing of the machinery, each probe being arranged to detect whether or not the blade passes over that probe;

wherein the edge detector determines the axial position of the edge of the blade as the position of the boundary between those tip detection probes which detect passage of the blade tip thereover and those tip detection probes which detect no passage of the blade tip thereover.

2. The edge detector of claim 1, wherein the tip detection probes are axially spaced at equal intervals.

3. The edge detector of claim 1, wherein the tip detection probes are spaced circumferentially in a helical arrangement.

4. The edge detector of claim 1 where the tip detection probes are optical probes.

5. The edge detector of claim 2 where the tip detection probes are optical probes.

6. The edge detector of claim 1 wherein the tip detection probes are capacitance probes.

7. The edge detector of claim 2 wherein the tip detection probes are capacitance probes.

8. The edge detector of claim 1, having two or more circumferentially spaced sets of the axially spaced tip detection probes.

9. A blade tip timing apparatus having:

the edge detector of claim 1 for determining the axial position of the leading or trailing edge of a rotating blade;

a row of blade tip timing probes locatable within the casing to measure the times at which a position on the tip of the blade passes the blade tip timing probes;

a processor unit which receives axial position and timing data from respectively the edge detector and the blade tip timing probes, and calculates therefrom the vibration of the blade.

10. The blade tip timing apparatus of claim 9, wherein the blade tip timing probes are adjacent the edge of the blade whose axial position is detected by the edge detector.

11. The blade tip timing apparatus of claim 9, wherein the processor unit employs a torsional vibration model and the axial position data to calculate the axial distance of the axis of torsional vibration of the blade from the blade tip timing probes, preliminary to calculating the vibration of the blade from the timing data.

12. The blade tip timing apparatus of claim 9, wherein the processor unit employs results of an experimental vibration test to determine the axial distance of the axis of torsional vibration of the blade from the blade tip timing probes, preliminary to calculating the vibration of the blade from the timing data.

13. A rotating machinery casing fitted with the edge detector, the edge detector including:

a set of axially spaced tip detection probes locatable within a casing of the machinery, each probe being arranged to detect whether or not the blade tip passes over that probe;

wherein the edge detector determines the axial position of the edge of the blade as the position of the boundary between those tip detection probes which detect passage of the blade tip thereover and those tip detection probes which detect no passage of the blade tip thereover.

14. A rotating machinery casing according to claim 13, wherein the tip detection probes are axially spaced at equal intervals.

15. A rotating machinery casing according to claim 13, wherein the tip detection probes are spaced circumferentially in a helical arrangement.

16. A rotating machinery casing according to claim 13 having two or more circumferentially spaced sets of the axially spaced tip detection probes.

17. Rotating machinery having the rotating machinery casing of claim 13.