US 8,576,392 B2 · Multiplexed optical fiber crack sensor

Abstract

An optical fiber crack detector that includes a plurality of FBG sensors positioned within one or more fibers that are operable to reflect a defined wavelength of an optical input beam. The crack detector includes a light source for generating the optical input beam that propagates down the optical fiber and interacts with the FBG sensors. A wavelength of the optical beam that is reflected by the FBG sensors is detected, and if a crack in the component damages the fiber between an FBG sensor and the detector circuit, where one or more of the reflected signals are not received, the detector knows that a crack has occurred. By strategically placing a plurality of the FBG sensors along the fiber, a crack that damages the fiber in multiple locations between multiple FBG sensors, or in multiple fibers, can provide an indication of the length of the crack.

Claims20

Dependent claims

A crack sensor for detecting cracks in a component, said sensor comprising:

at least one light source generating an optical beam;
at least one optical fiber receiving the optical beam from the at least one light source, said optical fiber including a fiber core through which the optical beam propagates and a plurality of spaced apart fiber Bragg gratings formed in the core, each fiber Bragg grating being operable to reflect a predefined and different wavelength of the optical beam back along the optical fiber and allow other wavelengths in the optical beam to propagate through the fiber Bragg grating;
and
a detector for detecting the reflected wavelengths of the optical beam from the fiber Bragg gratings, wherein a crack that forms in the component that damages or severs the fiber between fiber Bragg gratings causes loss of reflected wavelengths from at least some of the fiber Bragg gratings to identify the location of the crack.

1 more element

A gas turbine comprising:

a shaft rotatably provided along a center line of the turbine;
a compressor section responsive to a working fluid and being operable to compress the working fluid to produce a compressed working fluid;
a combustion section in fluid communication with the compressor section that receives the compressed working fluid, said combustion section mixing the compressed working fluid with a fuel and combusting the compressed fluid and fuel mixture to produce a hot working fluid;
a turbine section in fluid communication with the combustion section, said turbine section expanding the hot working fluid to produce mechanical power through rotation of the shaft;
and
at least one crack sensor operatively coupled to a component in the engine, said at least one crack sensor including at least one optical fiber receiving an optical beam, said at least one optical fiber including a fiber core through which the optical beam propagates and a plurality of spaced apart fiber Bragg gratings formed in the core, each fiber Bragg grating being operable to reflect a predefined and different wavelength of the optical beam back along the optical fiber and allow other wavelengths in the optical beam to propagate through the fiber Bragg grating, wherein a crack that forms in the component that damages or severs the fiber between fiber Bragg gratings and causes loss of reflected wavelengths from at least some of the fiber Bragg gratings allows the sensor to identify the location of the crack.

3 more elements

Dependencies are inferred from the claim text.

Multiplexed optical fiber crack sensor

Life of this patent

Multiplexed optical fiber crack sensor

Life of this patent

Abstract

Claims20