Ultrasonic Waveguide Fluid Gap Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ultrasonic measurement devices face challenges with wave disturbance and signal reduction when using materials with high acoustic field impedance, and environmental issues like condensation affect measurements, especially at high pressures.
Innovation Solution
A measuring device design where the rear surface of the waveguide is spaced from a reflection surface by a gap filled with a fluid or solid, with a specific thickness relationship that minimizes wave disturbance, allowing for robust support and high reception amplitudes, even with materials like metal or fiber-reinforced plastics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rear surface of the waveguide is directly supported by a housing wall made of materials with high acoustic field impedance (metal or fiber-reinforced plastics), then the waveguide is robustly supported, but a strong disturbance of the Lamb wave results, leading to significant reduction in the amplitude of received signals
Solution Approach 1:
A fluid layer is introduced as an intermediary substance between the waveguide rear surface and the reflective surface of the housing wall. This fluid layer acts as an acoustic buffer that prevents direct mechanical contact between the waveguide and high-impedance housing materials, thereby reducing Lamb wave disturbance while maintaining structural support. The fluid layer's acoustic properties are specifically selected to minimize wave reflection and maximize signal transmission.
2Device complexity
If the rear surface of the waveguide is exposed, then complex measures to protect from environmental influences are avoided, but condensation of liquids on this surface can impair the measurement
Solution Approach 1:
The fluid layer serves as a protective intermediary between the waveguide rear surface and the external environment. This fluid barrier prevents condensation and environmental contaminants from directly contacting the waveguide surface, thereby protecting measurement accuracy without requiring additional complex protective structures or sealing mechanisms.
3Ease of manufacture
If the waveguide is made of thin sheet metal to achieve wave guidance, then wave propagation is enabled, but only relatively low pressures can be used in the measuring section
Solution Approach 1:
The reflective surface of the housing structure acts as a counterbalancing support element that provides mechanical reinforcement to the thin sheet metal waveguide. By positioning the reflective surface at a specific distance behind the waveguide, structural stability is enhanced without compromising wave propagation characteristics, thereby enabling the use of thin waveguide materials while withstanding higher pressures.
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 design enables reliable ultrasonic measurements with reduced signal loss and increased robustness, allowing for accurate determination of fluid properties and pressures, even at high pressures, while tolerating variations in manufacturing tolerances.
Implementation Method 1
The control device is configured to control the first ultrasonic transducer in such a way that the first ultrasonic transducer generates a guided wave with a predetermined oscillation frequency f
Implementation Method 2
Patent application JP 2020 1 06343A discloses an ultrasonic measurement method in which guided waves leaking into a gas space are reflected and converted back into guided waves
Implementation Method 3
The Lamb wave can be excited, for example, by an ultrasonic transducer arranged on the back or end face of the waveguide
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Measuring device (1) for determining a measured quantity, comprising a first and second ultrasonic transducer (2, 3), wherein a guided wave (5) propagates in the waveguide (6) parallel to a back surface (7) of the waveguide (6), wherein the back surface (7) of the waveguide (6) is directed towards a reflective surface (9) of the measuring device (1) at least in a waveguide section (8, 30, 31) of the waveguide (6) and is spaced apart from it by an intermediate space (15), wherein the measuring device (1) is designed such that at least during the determination of the measured quantity a fluid layer (13) or a solid (14) fills the intermediate space (15) between the waveguide (6) and the reflective surface (9) at least in the waveguide section (8, 30, 31) of the waveguide (6), wherein the distance (16) between the back surface (7) and the reflective surface (9) and thus the thickness D of the fluid layer (13) or of the solid (14) at least in the shaft guide section (8, 30,31) the relationship D=2n±Δ−14f1cf2−1cph2 with the vibration frequency f, the speed of sound cf in the fluid layer (13) or the solid (14) and the phase velocity cph in the waveguide, where the design variable n is a positive integer and the deviation Δ is either equal to zero or positive and less than 0.7 or less than 0.5.