Ultrasonic Flow Meter Transducer Arrangement for Pulse Isolation
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Solution Overview
Problem
Ultrasonic flow measuring devices face challenges in achieving accurate flow velocity measurements due to interference from indirect fluid sound components, leading to significant measurement errors, especially when using clamp-in technologies where the pipe wall is excited, causing superimposed sound components to affect transit time measurements.
Innovation Solution
The ultrasonic flow measuring device employs a specific arrangement of transducers to temporally isolate the direct pulse by positioning them with a secant angle and axial distance that minimizes overlap with other sound components, allowing for precise evaluation of the direct pulse using classical methods like Hilbert transformation, thereby eliminating interference from indirect fluid sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If clamp-in technology is used where the pipe wall is excited, then non-diametric or off-center paths can be realized, but measurement errors increase due to superimposed sound components from pipe wall excitation
Solution Approach 1:
The patent segments the received ultrasonic signal into multiple partial pulses corresponding to different propagation paths (direct path, reflected paths, pipe wall paths). By temporally separating these segments and selecting only the direct path pulse for evaluation, the system eliminates interference from pipe wall excitation while maintaining the versatility of clamp-in technology
Solution Approach 2:
The patent extracts the direct path pulse from the superimposed signal by identifying its specific time window based on geometric calculations. This extraction isolates the useful measurement signal from harmful pipe wall excitation components, resolving the contradiction between measurement versatility and precision
2Quantity of substance
If multiple reflections and indirect fluid sound components are present, then comprehensive signal capture is achieved, but pulse overlay causes significant measurement errors
Solution Approach 1:
The patent converts the harmful effect of multiple reflections into a benefit by using the known geometry of the system to calculate expected arrival times of different path components. This allows the system to identify and isolate the direct path pulse even in the presence of numerous reflected signals, transforming signal contamination into a structured problem with a known solution
3Measurement precision
If algorithm-based pulse separation or filtering is used, then interference from indirect fluid sound can be reduced, but measurement errors remain in the double-digit percentage range
Solution Approach 1:
The patent replaces complex algorithm-based signal separation with a geometric-time based selection method. By calculating the expected arrival time of the direct path pulse based on transducer positions and sound speed, the system directly selects the appropriate signal segment without requiring iterative filtering or separation algorithms, achieving high precision with simpler processing
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 results in negligible measurement errors by isolating the direct pulse from other fluid sound components, enabling more accurate flow velocity measurements compared to traditional methods that rely on algorithms for pulse separation or filtering.
Implementation Method 1
The ultrasonic transducers used to generate ultrasound have a vibrating body, often ceramic. With its help, for example, an electrical signal is converted into ultrasound and vice versa based on the piezoelectric effect.
Implementation Method 2
The resulting transit time difference is calculated using geometric variables to obtain an average flow velocity of the fluid.
Data Source
Figure 1a~1b
Figure 2~3b
AI summary
An ultrasonic flow measuring device (10) for determining the flow velocity of a fluid flowing in a conduit (12) is described, comprising at least one measuring path (18) in which a first ultrasonic transducer (16a) and a second ultrasonic transducer (16b) are arranged opposite each other with the flowing fluid between them, and an evaluation unit configured to calculate the flow velocity from a transit-time difference of ultrasonic pulses along the measuring path (18) in the direction with the flow (14) and against the flow (14). The ultrasonic transducers (16a-b) are positioned such that a specific partial pulse is temporally isolated in a received signal of the respective receiving ultrasonic transducer (16a-b), wherein the partial pulse corresponds to a direct sound, a reflected sound, an axially refracted fluid sound, or an azimuthally refracted fluid sound.