Clamp-On Ultrasonic Flowmeter for Gas in Non-Metallic Tubes
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Solution Overview
Problem
Existing ultrasonic flowmeters struggle to accurately measure gas flow rates in non-metallic tubes due to low signal intensity and interference between longitudinal and shear waves, and thermal flow sensors face instability and maintenance issues with rectifying plates.
Innovation Solution
An ultrasonic flowmeter design that includes first and second wedge members forming specific angles with the tube surface to excite both longitudinal and shear waves with a mixing ratio of 10% or less, using acoustic coupling members and support portions to enhance signal transmission and measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a clamp-on type ultrasonic flowmeter is used to measure gas flow rate from the outside of piping, then the rectifying plate is unnecessary and pressure loss is avoided, but the signal intensity decreases due to the smaller density and slower sound velocity of gas compared to liquid
Solution Approach 1:
The patent introduces a wedge member as an intermediary component between the ultrasonic element and the gas flow path. The wedge member generates longitudinal waves in the gas by converting ultrasonic vibrations, acting as a mediator that enhances signal transmission from the ultrasonic element to the gas, thereby solving the low signal intensity problem in gas flow measurement
Solution Approach 2:
The patent changes the measurement approach by using longitudinal waves generated through the wedge member instead of direct ultrasonic transmission. This parameter change in wave generation method enables effective signal transmission in gas environments where direct ultrasonic measurement fails due to low density and slow sound velocity
2Measurement precision
If thermal flow sensor is arranged in the flow path, then flow rate measurement is possible, but pressure loss is generated by the rectifying plate and the heaters are vulnerable to dirt and clogging
Solution Approach 1:
The patent replaces the thermal flow sensor's mechanical and thermal components (heaters, rectifying plates) with an ultrasonic wave-based measurement system. The ultrasonic flowmeter uses acoustic waves to measure flow rate without physical contact with the fluid, eliminating the mechanical components that cause pressure loss and are susceptible to clogging
Solution Approach 2:
The wedge member serves as an intermediary that enables non-contact measurement of gas flow rate through ultrasonic wave generation. This intermediary approach allows flow rate measurement without the measurement device being directly exposed to the fluid, thereby eliminating clogging and maintenance issues
3Adaptability or versatility
If the tube excites both longitudinal wave and shear wave, then measurement can be performed, but the signal intensity decreases due to interference between the two wave types
Solution Approach 1:
The patent applies local quality by designing the wedge member with specific geometric characteristics (angle, material properties) that locally enhance the generation of longitudinal waves while suppressing shear wave generation. This localized optimization ensures that only the useful longitudinal waves are generated in the measurement region, eliminating interference and maintaining high signal intensity
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
Enables accurate measurement of gas flow rates in non-metallic tubes by utilizing the high signal intensity of longitudinal waves, reducing interference, and maintaining measurement stability while minimizing device size and maintenance needs.
Implementation Method 1
a first ultrasonic element 11 that transmits and receives an ultrasonic signal; a second ultrasonic element 12 that transmits and receives an ultrasonic signal
Implementation Method 2
measures a flow rate of the gas flowing in the tube based on a propagation time difference of a longitudinal wave, excited in the tube, among the ultrasonic signals transmitted and received between the first ultrasonic element and the second ultrasonic element
Implementation Method 3
a first wedge member 14 in which a first surface opposing the first ultrasonic element and a second surface opposing an outer surface of the tube form a first angle, the first wedge member propagating the ultrasonic signal
Implementation Method 4
The first angle of the first wedge member and the second angle of the second wedge member are configured such that the tube excites both a longitudinal wave and a shear wave
Implementation Method 5
a mixing ratio of the shear wave to the longitudinal wave is 10% or less
Implementation Method 6
the tube excites both a longitudinal wave and a shear wave
Data Source
AI summary
To enable accurate measurement of a flow rate of a gas flowing in a non-metallic tube. An ultrasonic flowmeter includes a first wedge member having a first angle, a second wedge member having a second angle, and a flow rate measurement unit that measures a flow rate of a gas based on a propagation time difference of a longitudinal wave excited by a tube. The first angle and the second angle are configured such that the tube excites both a longitudinal wave and a shear wave, and a mixing ratio of the shear wave to the longitudinal wave is 10% or less.