Fiber Bragg Grating Pressure Sensor for Aircraft Fire Suppression
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Solution Overview
Problem
Existing pressure sensors for pressure bottles, such as those used in aircraft fire suppression systems, require additional temperature sensors due to temperature-dependent strain measurements, and are susceptible to electromagnetic interference, moisture, and fatigue.
Innovation Solution
A fiber Bragg grating-based pressure sensor system with two or more FBGs attached to a diaphragm seal, where one FBG is at the center and another at a radial distance, providing built-in temperature compensation and immunity to interference by using a laser to output white light and processing circuitry to determine pressure changes based on wavelength shifts without an external temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pressure sensors are used, then pressure measurement can be achieved, but additional temperature sensors are required due to temperature-dependent strain measurements
Solution Approach 1:
The patent combines multiple FBGs into a single integrated sensor assembly that simultaneously measures both pressure and temperature effects. By merging the pressure-sensitive FBGs with temperature-compensation FBGs in one structure, the system eliminates the need for separate temperature sensors while maintaining measurement accuracy.
Solution Approach 2:
The FBG assembly serves multiple functions: it measures pressure through wavelength shift detection while simultaneously providing temperature compensation through strategically positioned reference FBGs. This multi-functional design replaces traditional separate pressure and temperature sensing systems.
2Reliability
If traditional pressure sensors are used, then pressure monitoring is possible, but they are susceptible to electromagnetic interference
Solution Approach 1:
The patent replaces traditional electrical pressure sensing mechanisms with an optical FBG-based system. By substituting electrical signals with optical wavelength measurements, the sensor becomes inherently immune to electromagnetic interference while maintaining pressure measurement capability.
3Reliability
If traditional pressure sensors are used, then pressure detection can be achieved, but they are susceptible to moisture and fatigue
Solution Approach 1:
The patent employs a flexible diaphragm structure that isolates the optical FBG sensors from direct exposure to moisture and mechanical fatigue. The diaphragm acts as a protective barrier while still transmitting pressure-induced deformations to the sensors, enhancing durability in harsh environments.
4Measurement precision
If multiple FBGs are used for temperature compensation, then temperature-independent pressure measurement is achieved, but the device complexity increases
Solution Approach 1:
The patent applies different functional characteristics to different locations of the FBG assembly. Pressure-sensitive FBGs are positioned where they experience maximum strain, while temperature-compensation FBGs are positioned as reference points. This localized functional differentiation achieves accurate temperature-independent measurement without requiring excessive numbers of sensors.
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
The system allows for temperature-independent pressure measurement, immunity to electromagnetic interference, moisture, and fatigue, improving sensitivity and reducing the need for additional temperature sensors.
Implementation Method 1
Two or more fiber Bragg gratings (FBGs) may be attached to a diaphragm seal at an opening of the pressure bottle. The FBGs may include a same periodic variation in refractive index.
Implementation Method 2
The light source is a laser to output white light as the incident light to one or more optical fibers that include the two or more FBGs.
Implementation Method 3
the processing circuitry determines a shift from the baseline wavelength for each of the two or more FBGs based on the reflected light resulting from each of the two or more FBGs when the diaphragm seal is under strain
Data Source
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AI summary
A sensor to sense pressure in a pressure bottle and a method of assembling the sensor involve two or more fiber Bragg gratings (FBGs) affixed to a different radial location of a diaphragm seal of the pressure bottle. The sensor includes a light source to provide incident light to the two or more FBGs, and a photodetector to detect reflected light resulting from the two or more FBGs. Processing circuitry determines a pressure change in the pressure bottle based on the reflected light resulting from each of the two or more FBGs.