Broadband Acoustic Sensor for Non-Destructive Gas Pressure Measurement
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Solution Overview
Problem
Existing methods for measuring pressure and molar mass in cylindrical gas-filled enclosures, such as nuclear fuel rods, are either destructive or have low precision due to limitations in frequency range and sensitivity to gas absorption and enclosure imperfections.
Innovation Solution
A broadband acoustic sensor system that excites and measures gas resonances over a wide frequency band, averaging effects to overcome absorption and imperfections, allowing for precise pressure and molar mass measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid coupling layer with thickness λ/4 is used for acoustic wave transmission, then acoustic wave transmission is improved, but the frequency range is limited to a small interval around resonance frequency
Solution Approach 1:
The patent changes the coupling layer thickness parameter from λ/4 to a range of 0.1λ to 0.5λ, and introduces a solid coupling layer with specific acoustic impedance characteristics. This parameter change enables the sensor to operate over a broader frequency range (at least 1 MHz wide) while maintaining reliable acoustic wave transmission, resolving the contradiction between transmission reliability and frequency adaptability.
2Measurement precision
If amplitude of gas resonances is used for pressure measurement, then pressure can be measured, but precision is reduced due to sensitivity to gas absorption and enclosure defects
Solution Approach 1:
The patent employs mechanical vibration of the enclosure wall as the primary measurement mechanism. By measuring the vibration characteristics (frequency and amplitude) of the enclosure wall itself rather than relying solely on gas resonance amplitude, the system achieves more stable and precise pressure measurements that are less sensitive to gas absorption and enclosure defects.
Solution Approach 2:
The patent implements a feedback mechanism where the measured vibration characteristics are used to calculate pressure and molar mass. The system continuously monitors the enclosure wall vibration and adjusts measurements to compensate for variations in gas absorption and enclosure properties, thereby maintaining high measurement precision and stability.
3Measurement precision
If destructive methods such as drilling are used, then direct access to gas pressure can be obtained, but the enclosure is damaged
Solution Approach 1:
The patent introduces the enclosure wall vibration as an intermediary mechanism. Instead of directly accessing the gas pressure through drilling, the system measures the vibration characteristics of the enclosure wall, which are influenced by the internal gas pressure. This intermediary approach enables non-destructive pressure measurement while preserving enclosure integrity.
4Measurement precision
If radioactive tracer gas is used for measurement, then gas properties can be determined, but the method cannot be applied to tubes containing the same radioactive tracer
Solution Approach 1:
The patent replaces radioactive tracer methods with acoustic/mechanical vibration measurement. By using the enclosure wall vibration characteristics to infer gas properties, the system eliminates the need for radioactive tracers, thereby enabling measurements in tubes that contain radioactive materials without safety concerns or measurement interference.
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 solution significantly increases measurement precision and allows for non-destructive assessment of gas pressure and molar mass in nuclear fuel rods, enabling detection of leaking rods and aiding in decision-making for nuclear power plant operations.
Implementation Method 1
The acoustic sensor allows the measurement of at least one physical parameter of the gas (2), such as for example the pressure of the gas in the enclosure and/or its molar mass, thanks to the amplitude of the waves reflected in the transducer
Implementation Method 2
at least one transducer (5) for on the one hand generating an acoustic signal causing the enclosure (1) and the gas (2) to vibrate, and on the other hand detecting an acoustic response signal characteristic of the vibrations of the gas (2) and the enclosure (1)
Data Source
Figure 1A~2
Figure 3A~3B
Figure 4~5
AI summary
The invention relates to a method for measuring the pressure and/or molar mass of a gas in a housing, the measure being carried out via an acoustic sensor, said acoustic sensor at least one transducer (5), an electric system (8) connected to the transducer (5) and a coupling layer (6) for coupling the transducer (5) to the housing (1), said method comprising the following steps: generating using the transducer (5) an excitation acoustic signal that vibrates the housing (1) and the gas (2) in a wide frequency band; detecting with the transducer (5) a response acoustic signal characteristic of the vibrations of the housing and the gas; analysing the response electric signals from the transducer (5) using the system (8); and deriving, essentially based on the gas (2) resonance frequencies, the speed of the acoustic waves in the gas, the molar mass of the gas and the pressure thereof. The invention also relates to an assembly for implementing the method.