Guided Wave Fluid Volume Detection Using Asymmetric Transducer Excitation
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Solution Overview
Problem
Existing ultrasonic flow measurement methods face challenges in achieving single-mode excitation of guided waves, leading to complex signal evaluation and reduced mode purity, which affects the accuracy of fluid flow measurements.
Innovation Solution
The method involves using two transmission and two reception vibration converters to selectively excite and record guided waves, with controlled delay times and phase relationships to achieve destructive or constructive interference, ensuring mode purity and selective excitation of specific vibration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple vibration modes are excited simultaneously, then the measurement can be performed, but the mode purity decreases and signal evaluation becomes complex
Solution Approach 1:
The patent applies asymmetry by using different excitation signals for the two transmitting transducers. Specifically, the first transmitting transducer is excited with a sinusoidal signal while the second transmitting transducer is excited with a different sinusoidal signal having a phase shift. This asymmetric excitation approach creates destructive interference for unwanted vibration modes while maintaining constructive interference for the desired mode, thereby achieving high mode purity without complex signal evaluation
Solution Approach 2:
The patent changes the excitation parameters (frequency and phase) of the transmitting transducers to selectively excite specific vibration modes. By adjusting the phase difference between the excitation signals and selecting appropriate frequencies, the system achieves mode-selective excitation. This parameter control allows the desired vibration mode to be excited with high purity while suppressing other modes, resolving the contradiction between measurement capability and mode purity
2Reliability
If complex lithography is used to deposit electrode structures, then transducer performance improves, but manufacturing complexity and precision requirements increase
Solution Approach 1:
The patent extracts the complex electrode structure requirements by using a simplified interdigital transducer design. Instead of requiring complex high-precision lithography to deposit intricate electrode patterns, the invention uses a simpler electrode configuration that still achieves effective excitation of guided waves. This extraction of the complex electrode structure requirement reduces manufacturing complexity while maintaining transducer performance through the use of phase-controlled excitation signals
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 simplifies the measurement device structure, enhances mode purity, and improves the accuracy of fluid flow measurements by selectively amplifying or damping specific vibration modes, resulting in a higher signal-to-noise ratio.
Implementation Method 1
at least one ultrasonic transducer is used to couple an ultrasonic wave into a fluid flowing through a measuring tube
Implementation Method 2
a wave guided in the side wall of the measuring tube is excited by a first and second transmitting vibration transducer arranged on a side wall of the measuring tube
Implementation Method 3
is guided directly in the side wall or indirectly via the fluid to a first and second receiving vibration transducer arranged on the or a further side wall of the measuring tube
Implementation Method 4
the specific oscillation mode of the guided wave to be excited is at least partially canceled out in at least one direction of propagation by destructive interference of the partial waves excited by the individual transmitting oscillators
Data Source
Figure 1~2
Figure 3
AI summary
Method for determining a fluid quantity relating to a fluid and/or a fluid flow of the fluid using a measuring device (1) comprising a measuring tube (2) that receives the fluid and/or through which the fluid flows, wherein a first and second transmitting vibration transducer (7, 8) arranged on a side wall (6) of the measuring tube (2) jointly excite a wave guided in the side wall (6) of the measuring tube (2) and guide it directly in the side wall (6) or indirectly via the fluid to a first and second receiving vibration transducer (12, 13) arranged on the or a further side wall (11) of the measuring tube (2) or along a propagation path back to the transmitting vibration transducers (7, 8) and there to determine measurement data, wherein the fluid information is determined as a function of the measurement data, wherein - on the one hand the first and the second transmitting vibration transducer (7, 8) are controlled to excite the guided wave in such a way,that the temporal profile of the oscillation amplitude of the second transmitting oscillator (8) corresponds to the temporal profile of the oscillation amplitude of the first transmitting oscillator (7) delayed by a delay time, - and/or wherein, on the other hand, to determine the measurement data, output signals of the first receiving oscillator (13) or transmitting oscillator (7) and output signals of the second receiving oscillator (12) or transmitting oscillator (8) delayed by a further delay time are added to or subtracted from each other.