Acoustic Flexural Order Level Sensor for Aerated Fluids
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Solution Overview
Problem
Existing liquid level sensors fail to accurately detect fluid levels in aerated fluids due to interference from bubbles, often requiring baffles that complicate installation and increase costs.
Innovation Solution
A liquid level sensor using a rod with a wave generation unit that produces flexural waves with higher order longitudinal shear, trapping specific orders to isolate and analyze the wave propagation, allowing direct detection of fluid levels without external baffles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a baffle is incorporated around the sensor to prevent bubbles from interfering, then measurement precision is improved, but device complexity and installation cost increase
Solution Approach 1:
The harmful effect of bubbles is eliminated by extracting or removing the baffle component entirely. The patent achieves bubble immunity through the inherent properties of higher order flexural waves with longitudinal shear, which do not interact with aerated fluids, thus taking out the need for protective baffles and simplifying the device structure.
Solution Approach 2:
The patent changes the wave propagation parameters by using higher order flexural waves with substantial longitudinal shear at the rod surface, rather than conventional extensional waves. This parameter change in wave mode enables direct detection in aerated fluids without requiring additional protective structures.
2Measurement precision
If a baffle is incorporated around the sensor to prevent bubbles from interfering, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The baffle component is extracted or removed from the sensor system. The invention achieves bubble resistance through the physical properties of higher order flexural waves, eliminating the need for complex installation procedures required for baffle-based solutions.
3Reliability
If higher order flexural waves with longitudinal shear are used, then reliability in aerated fluids is improved, but device complexity increases due to wave trapping requirements
Solution Approach 1:
The rod structure is designed with local quality variations, specifically changing the diameter along its length to create a larger diameter first portion and a smaller diameter second portion. This local geometric modification enables wave trapping of higher order modes in the first portion while allowing fundamental modes to propagate to the second portion, achieving reliable aerated fluid detection without excessive overall complexity.
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 detection of fluid levels in aerated fluids by isolating sensitive flexural wave orders, reducing interference from bubbles and simplifying installation, thus improving sensor sensitivity and reducing costs.
Implementation Method 1
a wave generation unit affixed to one end of the rod, where the wave generation unit generates a flexural wave that propagates in a first order and at least one higher order with substantially longitudinal shear at a surface of the rod
Implementation Method 2
the rod is constructed so as to trap the higher order of the flexural wave in the first portion
Data Source
Figure 1A~1C
Figure 2A~2D
Figure 3A~4
AI summary
A liquid level sensor includes a rod having a first portion and a second portion, and a wave generation unit affixed to one end of the rod. The wave generation unit generates a wave group that propagates in at least a shear order and a flexural order, and the frequency of the shear wave is based on the diameter of the rod.