Ultrasonic Waveguide Sensor with Frequency-Selective Gratings
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Solution Overview
Problem
Traditional ultrasonic temperature measurement methods in nuclear reactors face challenges such as limited accuracy in temperature gradients and spatial distribution due to the need for average temperature measurements across large sections, and difficulties in distinguishing reflections from closely spaced notches, especially in harsh environments.
Innovation Solution
An ultrasonic waveguide sensor system with three gratings along its body, each configured to fully or partially reflect acoustic waves at different frequencies, utilizing frequency-selective reflection to accurately determine temperature and fluid level measurements by analyzing reflection signals from periodic discontinuities designed according to fractions of the acoustic wave's frequency and wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ultrasonic temperature measurement methods are used in nuclear reactors, then the sensor can operate in harsh environments, but the measurement precision is limited due to the need for average temperature measurements across large sections
Solution Approach 1:
The waveguide is divided into multiple measurement sections by introducing periodic discontinuities (gratings) at specific locations. Each grating reflects ultrasonic waves at a unique frequency, enabling independent temperature measurement at each segment location. This segmentation transforms a single average temperature measurement into multiple localized temperature measurements, significantly improving spatial resolution and measurement precision without requiring multiple separate sensors.
Solution Approach 2:
Different sections of the waveguide are equipped with gratings that have distinct geometric properties (spacing, depth, orientation) tailored to reflect specific frequencies. This local differentiation allows each measurement point to be optimized for its specific location, enabling precise local temperature measurements while maintaining overall system operation in harsh nuclear reactor environments.
2Measurement precision
If multiple notches are used for distributed measurements, then spatial distribution information can be obtained, but the difficulty in distinguishing reflections from closely spaced notches increases
Solution Approach 1:
The gratings are designed with varying geometric parameters (spacing between discontinuities, depth, orientation) such that each grating reflects ultrasonic waves at a distinct frequency. This parameter differentiation creates unique frequency signatures for each measurement location, making it easy to distinguish reflections from closely spaced gratings in the frequency domain, thereby solving the signal distinction problem.
Solution Approach 2:
The gratings are pre-configured with specific geometric properties during manufacturing to ensure they reflect at predetermined, well-separated frequencies. This preliminary design ensures that when ultrasonic waves encounter multiple gratings, the reflections are already differentiated by frequency, eliminating the need for complex signal processing to distinguish between closely spaced reflections.
3Area of stationary object
If a single sensor is used to obtain multiple measurements, then space for sensor installation is reduced, but the device complexity increases
Solution Approach 1:
A single waveguide structure performs multiple temperature measurement functions simultaneously by incorporating multiple gratings at different locations with different geometric properties. This multi-functional design allows one sensor to replace what would traditionally require multiple separate sensors, reducing installation space while the modular grating design keeps the complexity manageable through standardized geometric variations.
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 achieves precise multi-point temperature measurements and fluid level detection with improved accuracy and reliability, capable of operating in extreme temperatures up to 2800°C, reducing maintenance costs and enhancing the reliability of nuclear reactor operations.
Implementation Method 1
three gratings along the body where each of the three gratings is configured to fully or partially reflect an acoustic wave on the waveguide at a different frequency than the other gratings of the three gratings
Data Source
AI summary
An apparatus and method for distributed physical parameter measurements of the surrounding environment is disclosed. The apparatus can include a waveguide with an elongated body configured with three gratings along the body where each of the three gratings is configured to fully or partially reflect an acoustic wave on the waveguide at a different frequency than the other gratings of the three gratings. Further, each of the three gratings can comprise discontinuities in the grating configured to reflect one or more frequencies of acoustic waves, and each of the discontinuities for each of the three gratings has an internal geometry configured according to fractions of an acoustic wave's frequency and corresponding wavelength.