Integrated Optical Fiber Flow Velocity Sensor for High and Low Range Measurement
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Solution Overview
Problem
Existing flow velocity sensors have limitations in microfluidic and low-velocity detection, with complex electric circuits and difficulty in integrating different sensing elements for improved accuracy.
Innovation Solution
An optical fiber flow velocity measuring apparatus and method that integrates high and low-range sensing using two optical fiber sensing elements with wavelength division multiplexing, demodulation, and a flow velocity arithmetic unit to determine the final flow velocity based on critical value settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow velocity conversion devices based on different principles are integrated to improve accuracy, then measurement precision is improved, but device complexity increases due to complicated electric circuits
Solution Approach 1:
The patent replaces traditional electrical signal processing systems with an optical fiber-based sensing system. Optical fiber sensing elements directly convert flow velocity information into optical signal wavelength changes, eliminating the need for complex electrical-to-optical conversion circuits and reducing overall device complexity while maintaining high measurement precision
Solution Approach 2:
The patent integrates multiple sensing functions into a single optical fiber sensor assembly that can simultaneously measure both high-velocity and low-velocity flow conditions. By using wavelength division multiplexing with multiple optical fiber gratings, the system achieves multi-range measurement capability without requiring separate electrical conversion devices for each range
2Measurement precision
If different sensing elements of different flow velocity sensors are integrated in one apparatus, then measurement precision is improved, but device complexity increases due to difficulty of integration
Solution Approach 1:
The patent merges multiple sensing elements (first and second optical fiber sensing elements with different gratings) into a single integrated optical fiber sensor assembly. The sensing elements are coupled through wavelength division multiplexing, allowing them to be integrated in one apparatus while maintaining their individual measurement functions for different flow velocity ranges
Solution Approach 2:
The patent uses wavelength division multiplexing as an intermediary mechanism to integrate different optical fiber sensing elements. This intermediary allows multiple sensing elements with different measurement ranges to be combined in one apparatus without requiring complex electrical integration, as each element operates independently through its designated wavelength channel
3Measurement precision
If hot wire sensor is used for microfluidic and low-velocity detection, then measurement precision is improved, but adaptability decreases due to limited range
Solution Approach 1:
The patent segments the measurement range into multiple zones by employing different optical fiber sensing elements optimized for different velocity ranges. The first optical fiber sensing element handles high-velocity measurements while the second element handles low-velocity measurements, with each segment contributing its specialized measurement capability to the integrated system
Solution Approach 2:
The patent implements dynamic range adaptation by automatically selecting or weighting the output from different sensing elements based on the current flow velocity conditions. This dynamic approach allows the system to maintain high measurement precision across the entire velocity spectrum, adapting to both microfluidic low-velocity and macrofluidic high-velocity situations
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
Achieves improved accuracy and sensitivity by combining low and high-range optical fiber sensing elements, selecting the appropriate flow velocity based on measurement conditions, and simplifying the overall structure for easy implementation.
Implementation Method 1
both ends of the single-mode optical fiber are connected into the wavelength division multiplexer
Implementation Method 2
an optical fiber grating demodulator connected with the wavelength division multiplexer through a common optical fiber
Implementation Method 3
the first optical fiber sensing element comprises an elastic diaphragm, a first optical fiber grating, and a second optical fiber grating, wherein the first optical fiber grating and the second optical fiber grating are attached to two sides of the elastic diaphragm, respectively
Implementation Method 4
a pump light source connected with the wavelength division multiplexer through a common optical fiber
Data Source
AI summary
Disclosed is an optical fiber flow velocity measuring apparatus and method integrating high and low ranges. The apparatus includes an integrated optical fiber flow velocity sensor, the integrated optical fiber flow velocity sensor includes a sensor body; a fluid channel, a fluid through hole, a full-pressure channel, a static-pressure channel, a low-pressure chamber and a high-pressure chamber are provided inside the sensor body; a first optical fiber sensing element is provided between the low-pressure chamber and the high-pressure chamber; a second optical fiber sensing element is provided in the fluid through hole and is perpendicular to a flow direction of a fluid to be measured; the first optical fiber sensing element and the second optical fiber sensing element are sequentially connected in series through a single-mode optical fiber; both ends of the single-mode optical fiber are connected into a wavelength division multiplexer; a pump light source is connected with the wavelength division multiplexer through a common optical fiber; an optical fiber grating demodulator is connected with the wavelength division multiplexer through a common optical fiber; and a flow velocity arithmetic unit is electrically connected with a optical fiber grating demodulator. It's an object of the present disclosure to solve the problems that the electric circuit is too complicated and that it is not easy to integrate in one apparatus when flow velocity conversion devices based on different principles are integrated.