Clamp-on Ultrasonic Flowmeter Using Circumferential Resonance Modes
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Solution Overview
Problem
Ultrasonic clamp-on flowmeters face limitations in stability, linearity at low flow speeds, and inability to measure flow profiles, requiring complex manual alignment and setup parameters, which restricts their application and accuracy.
Innovation Solution
A novel clamp-on ultrasonic flow metering technique that collectively excites and receives circumferential modes of the pipe, utilizing broad-band transducer excitation to record frequency/mode-dependent mode-conversion rates, enabling accurate measurement of flow velocity profiles and other fluid parameters through analytical or machine learning algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clamp-on ultrasonic flowmeters are used for non-invasive flow measurement, then installation simplicity is improved, but measurement precision and stability deteriorate
Solution Approach 1:
The patent applies mechanical vibration by exciting circumferential resonance modes in the pipe wall using ultrasonic vibrations. The transducers generate vibrational waves that propagate through the pipe wall and interact with the flowing fluid, enabling flow measurement through resonance mode analysis rather than direct acoustic path measurement, thereby improving precision while maintaining clamp-on simplicity
Solution Approach 2:
The patent changes the measurement parameter from direct acoustic transit time to circumferential resonance mode frequencies and attenuation characteristics. By measuring how the resonance modes are affected by fluid flow (mode conversion rates), the system achieves higher measurement precision through multiple measurable parameters including frequency shifts and quality factor changes
2Device complexity
If traditional transit-time methods are used in clamp-on meters, then device complexity is reduced, but measurement precision deteriorates at low flow speeds
Solution Approach 1:
The system uses circumferential resonance vibrations in the pipe wall that are sensitive to fluid flow effects. The resonance modes provide enhanced sensitivity at low flow velocities because the vibrational energy interacts more effectively with the fluid, creating measurable attenuation and frequency shifts that maintain linearity across a wider flow range including low speeds
Solution Approach 2:
The pipe wall itself acts as an intermediary medium that couples the ultrasonic transducers to the flowing fluid. By exciting resonance modes in the pipe wall, the system indirectly measures fluid flow through the interaction between wall vibrations and fluid, providing improved measurement precision especially at low velocities where direct acoustic methods fail
3Device complexity
If manual alignment and setup parameters are required for clamp-on transducers, then device complexity is reduced, but ease of operation deteriorates
Solution Approach 1:
The system performs self-alignment and self-characterization by automatically identifying the circumferential resonance modes of the pipe and determining optimal transducer positions. The measurement process itself provides the calibration information needed, eliminating the need for manual input of pipe dimensions, material properties, and speed of sound parameters by the user
Solution Approach 2:
The system performs preliminary characterization of the pipe and flow conditions during the initial measurement phase. By first identifying the resonance modes and their attenuation characteristics, the system automatically configures itself for optimal measurement, performing the alignment and parameter setup actions before actual flow measurement begins
4Device complexity
If single-mode ultrasonic measurement is used, then device complexity is reduced, but measurement precision deteriorates for flow profile measurement
Solution Approach 1:
The system segments the flow measurement into multiple circumferential resonance modes, each providing different spatial information about the flow profile. By measuring multiple modes simultaneously and analyzing their differential attenuation and frequency shifts, the system reconstructs detailed flow velocity profiles with high precision while maintaining a relatively simple clamp-on device configuration
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
This approach enhances the accuracy, repeatability, and simplicity of flow measurement, improving linearity across a wide range of flow speeds, and expands the application space by providing non-invasive, high-performance clamp-on sensors capable of measuring both laminar and turbulent flows.
Implementation Method 1
The pipe wall supports an infinite number of circumferential acoustic resonances
Implementation Method 2
Each of these modes, in contact with a fluid, can mode-convert into the flow at a different rate
Implementation Method 3
The mode-converted waves in the flow mode-convert back into the circumferential waves in the pipe once they travel across the flow
Implementation Method 4
the moving fluid alters the rate of mode-conversion as a function of the flow velocity
Data Source
AI summary
Clamp-on ultrasonic flow metering is provided by collectively exciting and receiving circumferential modes of the pipe. The pipe wall supports an infinite number of circumferential acoustic resonances. Each of these modes, in contact with a fluid, can mode-convert into the flow at a different rate. The mode-converted waves in the flow mode-convert back into the circumferential waves in the pipe once they travel across the flow. Furthermore, the moving fluid alters the rate of mode-conversion as a function of the flow velocity. At low frequencies, the wavelength is larger, thus the penetration depth in the flow is larger. As the frequency increases, the penetration depth becomes smaller. The variable penetration depth provides a methodology to sample the flow velocity profile.