Title: Methods and systems for detecting gas flow by photoacoustic signal generation

Abstract

A method for the detection of a gas flowing from a location in a structure is described. A hollow-core optical fiber is placed in a position adjacent the structure. The fiber includes a sound-conductive cladding layer; and further includes at least one aperture extending into its cross-sectional diameter. A beam of pulsed, optical is transmitted into the fiber with a tunable laser. The optical energy is characterized by a wavelength that can be absorbed by the gas that flows into the fiber through the aperture. This causes a temperature fluctuation in the region of gas absorption, which in turn generates an acoustic wave in the absorption region. The acoustic wave travels through the cladding layer, and can be detected with a microphone, so as to provide the location of gas flow, based on the recorded position and movement of the acoustic wave. A related system is also described.

Inventors:

Choudhury, Niloy; Challener, William Albert

Issue Date:

2018-03-06

Research Org.:

General Electric Co., Schenectady, NY (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1425841

Patent Number(s):

9910014

Application Number:

14/977,820

Assignee:

General Electric Company (Schenectady, NY)

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01M - TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

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G - PHYSICS G01 - MEASURING G01M - TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES

G01M3/24 - using infrasonic, sonic, or ultrasonic vibrations
G01M3/243 - {for pipes}
G01M3/38 - by using light

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G01N2021/1704 - {in gases}
G01N2021/1708 - {with piezotransducers
G01N21/17 - Systems in which incident light is modified in accordance with the properties of the material investigated
G01N21/1702 - {with opto-acoustic detection, e.g. for gases or analysing solids}
G01N2291/012 - Phase angle
G01N2291/021 - Gases
G01N29/02 - Analysing fluids
G01N29/024 - by measuring propagation velocity or propagation time of acoustic waves
G01N29/14 - using acoustic emission techniques {
G01N29/2418 - {using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics

G - PHYSICS G02 - OPTICS G02B - OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS

G02B6/02304 - {Core having lower refractive index than cladding, e.g. air filled, hollow core}
G02B6/02328 - {Hollow or gas filled core}
G02B6/02366 - {Single ring of structures, e.g. "air clad"}

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DOE Contract Number:  

AR0000543

Resource Type:

Patent

Resource Relation:

Patent File Date: 2015 Dec 22

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING