Fiber Optic Sensor for Flow Measurement

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Solution Overview

Problem

Conventional sensing devices are complex and difficult to implement for measuring fluid or gas flow parameters in hard-to-access areas, such as cooling flows or leakage flows through seals, due to their size and complexity.

Innovation Solution

A fiber optic sensing system with a housing and optical fibers secured perpendicular to the flow path, featuring Bragg gratings that measure differential, total pressure, and temperature by monitoring wavelength changes of light filtered through the gratings, allowing for compact and sensitive flow parameter measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sensing devices are used for measuring flow parameters in hard-to-access areas, then measurement capability is achieved, but device complexity and size increase

Engineering Contradiction:

Improveflow parameter measurementVSAvoidsensing device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical sensing devices with a fiber optic sensing system that uses optical fields instead of mechanical components. The fiber optic sensor with Bragg grating measures flow parameters (velocity, pressure, temperature) through optical wavelength changes, eliminating complex mechanical structures while maintaining measurement precision in hard-to-access areas

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention utilizes changes in optical parameters (wavelength, intensity) of light interacting with the fiber optic sensor in response to flow parameters. The Bragg grating reflects specific wavelengths that shift in response to strain, temperature, and pressure changes caused by fluid flow, enabling measurement through optical parameter changes rather than mechanical detection

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional sensing devices are used for measuring flow parameters in hard-to-access areas, then measurement capability is achieved, but device size increases

Engineering Contradiction:

Improveflow parameter measurementVSAvoidsensing device size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The fiber optic sensor replaces bulky mechanical sensing devices with a thin, flexible optical fiber that can be easily inserted into hard-to-access flow areas. The Bragg grating is written directly into the fiber core, eliminating the need for large mechanical sensor housings while maintaining measurement precision for flow velocity, pressure, and temperature

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Volume of moving object

If fiber optic sensor with Bragg grating is used, then device size is reduced, but measurement of multiple flow parameters becomes more complex

Engineering Contradiction:

Improvesensing device sizeVSAvoidmeasurement system complexity

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The fiber optic sensor with Bragg grating is designed to measure multiple flow parameters (velocity, pressure, temperature) simultaneously using a single integrated device. By strategically placing multiple Bragg gratings along the fiber and using appropriate housing configurations, the system achieves multi-functionality without increasing overall device size, as all measurements are obtained through optical wavelength analysis of the same fiber

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate measurement of flow velocity, pressure, and temperature in challenging environments with a compact and sensitive fiber optic sensing system, suitable for difficult-to-access areas like cooling flows or leakage flows through seals.

Implementation Method 1

a Bragg grating, a light source for transmitting light to the optical fiber, and a detector for detecting light filtered by the Bragg grating of the optical fiber

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Implementation Method 2

an optical fiber secured in the housing, a Bragg grating, a light source for transmitting light to the optical fiber

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

allow flow through the flow path to exert a pressure on the optical fiber and cause a deformation of the Bragg grating

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 4

monitoring wavelength changes of the detected light

Methodology Applied

Scientific EffectPhotoelasticity: Photoelasticity

Data Source

PatentUS8135245B2Fiber optic sensing system

Publication Date: 2012.03.13 GE INFRASTRUCTURE TECH LLC

AI summary

A fiber optic sensing system comprises a housing disposed in a flow path, and a fiber optic sensor. The fiber optic sensor comprises an optical fiber secured in the housing, a Bragg grating, a light source for transmitting light to the optical fiber, and a detector for detecting light filtered by the Bragg grating of the optical fiber and monitoring wavelength changes of the detected light. The fiber is substantially perpendicular to the flow path. The housing defines an opening at an upstream side to allow flow through the flow path to exert a pressure on the optical fiber and cause a deformation of the Bragg grating.