Ultrasonic Flow Velocity Measurement with Phase-Jump Correction
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Solution Overview
Problem
Conventional ultrasonic flow measurement methods suffer from measurement errors due to phase jumps caused by envelope deformation from drift effects such as temperature fluctuations, bubble formation, and particle interference, leading to inaccurate flow velocity determination.
Innovation Solution
The method corrects phase shifts by detecting and correcting phase jumps using the difference between current and previous transit times, allowing for a tolerance based on the carrier frequency period, and applying plausibility criteria to ensure accurate measurements under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional envelope-based temporal localization is used to determine reception time, then the method is simple to implement, but measurement precision deteriorates due to phase jumps caused by envelope deformation
Solution Approach 1:
The patent replaces the conventional envelope-based temporal localization method with a spectral analysis method using Fast Fourier Transform (FFT). Instead of relying on the maximum of the amplitude envelope to locate the ultrasonic signal, the invention transforms the received signal into the frequency domain and identifies the carrier frequency peak. This substitution eliminates phase jumps caused by envelope deformation while maintaining implementation feasibility through standard digital signal processing techniques.
2Measurement precision
If additional measurement paths with additional ultrasonic transducers are provided for greater measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent improves measurement precision by changing the parameter of temporal localization from envelope-based time domain analysis to spectral frequency domain analysis. By applying FFT and identifying the carrier frequency peak, the system achieves higher precision in determining reception time without adding more transducers or measurement paths. This parameter change in the signal processing approach resolves the contradiction between measurement accuracy and device 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
The method significantly enhances measurement robustness and accuracy by minimizing the impact of phase shifts, ensuring stable flow velocity measurements even under challenging conditions.
Implementation Method 1
Ultrasonic signals are transmitted and received by a pair of ultrasonic transducers arranged opposite each other on a pipe wall
Implementation Method 2
Fluid velocities in pipes and channels can be determined using ultrasonic measurement technology based on the differential transit time method
Implementation Method 3
The ultrasonic signals transported through the fluid are accelerated in the direction of flow and decelerated against the flow
Data Source
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AI summary
A method for measuring the flow velocity of a fluid (18) is specified, in which a first ultrasonic signal with the flow and a second ultrasonic signal against the flow are transmitted and received again on a measuring path (24) obliquely to a flow direction of the fluid (18), a first propagation time of the first ultrasonic signal and a second propagation time of the second ultrasonic signal are determined and the flow velocity is determined from a propagation time difference, wherein the ultrasonic signals have several periods of a carrier frequency (26) with an amplitude modulated according to an envelope (28), and for determining the propagation times a respective reception time (32) of an ultrasonic signal is established from a selected oscillation (30) of the ultrasonic signal, which oscillation is selected based on a profile, in particular a maximum of the envelope (28).In this case, a first difference between the first transit time and a previously determined first transit time and/or a second difference between the second transit time and a previously determined second transit time is calculated and, if the first difference and/or the second difference is a multiple of the period of the carrier frequency (26) up to a tolerance, the first transit time and/or the second transit time is corrected by the multiple of the period of the carrier frequency (26).