Vortex Flowmeter Signal Analysis for Bubble-Contaminated Fluids
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Solution Overview
Problem
Existing vortex flowmeters are prone to significant measurement errors due to the presence of foreign substances, such as gas bubbles, in the measured fluid, which are often not detected or detected late by the converter electronics.
Innovation Solution
A measuring system that includes a vortex sensor with a deformation body and sensor flag, capable of generating both a vortex frequency and resonance oscillations, coupled with converter electronics that analyze the vortex sensor signal to detect and quantify the presence of foreign substances by evaluating amplitude measurements and resonance frequencies, using algorithms to determine flow parameters and alert when threshold values are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional vortex flowmeters are used to measure fluid flow, then flow velocity measurement is achieved, but measurement precision deteriorates significantly when foreign substances like gas bubbles are present in the fluid
Solution Approach 1:
The evaluation of the vortex sensor signal is segmented into multiple frequency components. The converter electronics separate the signal into a first useful component (separation frequency) and a second useful component (mechanical resonance frequency), allowing independent analysis of each component to detect foreign substances while maintaining accurate flow measurement.
Solution Approach 2:
The system implements feedback by continuously monitoring the amplitude of the mechanical resonance frequency component and comparing it against threshold values. When the amplitude exceeds the threshold indicating foreign substance presence, the system can trigger alerts or adjust measurements, creating a closed-loop quality control mechanism.
2Speed
If the vortex sensor operates in high-speed fluid flow, then flow measurement capability is maintained, but detection of foreign substances becomes more difficult due to increased turbulence and noise
Solution Approach 1:
The invention exploits mechanical vibration by tuning the vortex sensor to its mechanical resonance frequency. When foreign substances are present, they modulate the amplitude of vibrations at this resonant frequency. By monitoring the amplitude modulation at the known resonance frequency, the system can detect foreign substances even in high-speed turbulent flow conditions where noise is high.
Solution Approach 2:
The system changes the parameter being monitored from purely frequency-based (separation frequency only) to include amplitude-based detection at the mechanical resonance frequency. This parameter change allows differentiation between normal flow-induced vibrations and foreign substance-induced vibrations, even in high-speed conditions.
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 system effectively detects and quantifies foreign substances in the fluid, reducing measurement errors by allowing for early detection and adjustment of flow parameter calculations, and can be easily retrofitted to existing systems through firmware upgrades.
Implementation Method 1
designed to generate vortices in the fluid flowing past it with a separation frequency (fV) that depends on the instantaneous flow velocity (u) of the fluid, such that a Kármán vortex street is formed
Implementation Method 2
which is configured, excited by the flowing medium, to perform mechanical oscillations around a static equilibrium position and to provide at least one vortex sensor signal representing such oscillations... corresponding to a pressure prevailing within the measured material, which is subject to periodic fluctuations
Implementation Method 3
the vortex sensor has a deformation body... which is configured, excited by the flowing medium, to perform mechanical oscillations around a static equilibrium position... the deformation body performs oscillatory movements in the detection direction, elastically deforming the deformation body
Implementation Method 4
the converter electronics are designed to determine digital vortex frequency measurements representing the separation frequency based on at least one vortex sensor signal, and to calculate and output measured values for at least one flow parameter
Data Source
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AI summary
The measurement system comprises a pipe (3) insertable into the course of said pipeline and having a lumen (3'), which is configured to guide the measurement substance flowing in the pipeline or to allow said measurement substance to flow through it, a bluff body (4) arranged in the lumen of the pipe (3) and configured to generate, in the measurement substance flowing past it, vortices having a shedding frequency, fV (fV ~ u), dependent on an instantaneous flow velocity, u, of said measurement substance, in such a way that a Kármán vortex street is formed in the fluid flowing downstream of the bluff body, a vortex sensor (1) arranged downstream of the bluff body, said vortex sensor having at least one mechanical resonance frequency, fR, and being configured, in a manner excited by the flowing measurement substance, to effect mechanical oscillations around a static rest position and to provide at least one vortex sensor signal (s1) which represents said oscillations and which contains a first useful component (s1N1), namely a spectral signal component representing oscillations of the vortex sensor (1) with the shedding frequency, fV, and which contains a useful component (s1N2), namely a spectral signal component (resonance component) representing resonance oscillations of the vortex sensor (1) with the mechanical resonance frequency, fR, thereof, and also converter electronics (2) for evaluating the at least one vortex sensor signal and for determining measurement values (XM) for the at least one flow parameter. The converter electronics (2) are configured to receive and evaluate the at least one vortex sensor signal, namely at least on the basis of the useful component (s1N1) to determine vortex frequency measurement values (Xf) representing the shedding frequency and also on the basis of the useful component (s1N2) to determine amplitude measurement values (Xs) representing an amplitude of the resonance oscillations of the vortex sensor (1). Moreover, the converter electronics (2) are furthermore configured, using one or more amplitude measurement values (Xs), to determine whether and/or to what extent the measurement substance contains foreign substances and/or to determine whether the measurement substance is embodied as a single- or multi-phase substance, and also, using one or more vortex frequency measurement values (Xf), to calculate, in particular digital, flow parameter measurement values (XM), namely measurement values for the at least one flow parameter.