Time-Reversed Ultrasonic Flow Meter for Irregular Channels
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Solution Overview
Problem
Conventional ultrasonic flow meters face challenges in accurately measuring flow speed and flow profiles, especially in irregular flow conditions and open channels, due to limitations in signal processing and transducer placement, which affect the precision and reliability of flow measurements.
Innovation Solution
The use of piezoelectric transducers to generate and receive ultrasonic signals, with a method involving the inversion of impulse response signals to enhance signal focusing and amplitude, allowing for improved signal-to-noise ratio and bit resolution adjustment to optimize flow measurement accuracy, including the ability to measure flow speed and conduit properties with a single transducer arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic flow meters are used, then flow speed measurement is possible, but measurement precision deteriorates in irregular flow conditions and open channels
Solution Approach 1:
The patent segments the ultrasonic signal into multiple propagation paths (direct path and reflected paths) to capture different flow information. By analyzing multiple signal paths, the system can accurately measure flow speed even in irregular flow conditions where a single path would be insufficient.
Solution Approach 2:
The patent introduces a temporal dimension by using time-reversed signals. The system records the impulse response, reverses it in time, and uses this reversed signal for measurement. This time-reversal technique focuses energy back to the source location, improving measurement precision in complex flow environments.
2Adaptability or versatility
If multiple propagation paths are used to determine average flow speed, then adaptability improves, but device complexity increases
Solution Approach 1:
The system uses the channel's own impulse response to create the measurement signal. By recording the impulse response and time-reversing it, the system automatically adapts to the specific channel characteristics without requiring complex external calibration or adjustment mechanisms.
Solution Approach 2:
The patent performs a preliminary measurement of the impulse response before actual flow measurement. This preliminary action characterizes the channel properties and enables the system to compensate for irregular flow profiles during subsequent measurements, reducing the need for complex real-time processing.
3Measurement precision
If signal amplitude is increased to improve signal-to-noise ratio, then measurement precision improves, but energy consumption increases
Solution Approach 1:
The patent inverts the impulse response in time to create the measurement signal. This time-reversal technique focuses the ultrasonic energy back to the source location, naturally amplifying the signal amplitude at the receiver without increasing the transmitted energy, thus improving signal-to-noise ratio energy-efficiently.
Solution Approach 2:
The system replaces mechanical amplification (increasing transducer power) with a signal processing approach (time-reversal). This substitution achieves signal amplification through constructive interference of the time-reversed waves, avoiding the energy consumption associated with mechanical amplification.
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 enables more precise and reliable flow speed measurements in various fluid conduits, including pipes and open channels, by concentrating the signal in space and time, improving the signal-to-noise ratio and allowing for simultaneous detection of flow speed and conduit properties without the need for separate signals or arrangements.
Implementation Method 1
sound transducers, e.g. in the form of piezoelectric elements, also known as piezoelectric transducers, are used to generate and to receive a test signal and a measuring signal
Implementation Method 2
evaluates the difference of propagation time of ultrasonic pulses propagating in and against flow direction
Implementation Method 3
travel time flow meters, sometimes also called transmission flow meters, which make use of a propagation time difference caused by the relative motion of source and medium
Implementation Method 4
an inverted version of the impulse response with respect to time is sent back through the same channel as a measuring signal, either in the reverse direction or in the same direction. This results in a signal with a peak at the origin, where the original source was
Data Source
AI summary
A method for determining a flow speed of a liquid in a fluid conduit is provided. During a signal-generating phase, an impulse signal is applied to a first ultrasonic transducer. A response signal is then received at a second ultrasonic transducer. A measuring signal is later derived from the response signal, wherein the derivation comprises reversing a signal portion with respect to time. During a measurement phase, a liquid moves with respect to the fluid conduit. The measuring signal is then applied to one of the two transducers and a response signal of the measuring signal is measured at the other transducer. A flow speed is derived from the response signal of the measuring signal.