Fluidic Oscillator Flow Meter with Protruding Electrodes
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Solution Overview
Problem
Fluidic oscillators used in liquid flow meters face challenges in achieving accurate measurements over a wide range of flow rates and pressure variations, with issues such as electrode polarization and noise interference affecting the reliability of flow measurements.
Innovation Solution
The implementation of a fluidic oscillator liquid flow meter with protruding sensing electrodes and an alternating driving signal to prevent electrode polarization, combined with a signal processor for filtering and comparing signals to distinguish valid fluid flow from noise and reverse flow, enhances measurement accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing electrodes are used to detect e.m.f. in the fluid flow, then flow measurement can be performed, but electrode polarization and chemical interactions cause noise and interference in the signal
Solution Approach 1:
The patent applies an alternating driving signal to the sensing electrodes at a frequency different from the fluid oscillation frequency. This periodic action prevents electrode polarization by continuously reversing the electrode polarity, thereby eliminating the harmful effect of polarization while maintaining the ability to detect flow-induced e.m.f. signals.
Solution Approach 2:
The patent uses a feedback mechanism where the detected signal from the sensing electrodes is processed and fed back to control the alternating driving signal. This feedback loop allows the system to adapt the driving signal parameters based on the detected flow conditions, maintaining measurement accuracy while compensating for electrode polarization effects.
2Adaptability or versatility
If the flow rate varies over a wide range (turn-down ratio of 300 to 1), then the meter can measure different flow rates, but measurement accuracy deteriorates at extreme flow rates
Solution Approach 1:
The patent changes the operating parameters of the fluidic oscillator and detector based on the flow rate range. By adjusting the alternating driving signal frequency and amplitude, and modifying the detector sensitivity, the system maintains optimal measurement accuracy across a wide flow rate range from 300:1 turn-down ratio.
Solution Approach 2:
The patent employs dynamic adjustment of the alternating driving signal parameters in response to varying flow conditions. The system dynamically adapts the driving signal frequency and amplitude to match the current flow rate, ensuring accurate measurements across the entire operating range rather than being optimized for a single flow condition.
3Adaptability or versatility
If the pressure of the fluid varies substantially, then the meter can handle different pressure conditions, but measurement accuracy is affected
Solution Approach 1:
The patent incorporates pressure compensation through feedback mechanisms that detect pressure variations and adjust the detector parameters accordingly. This feedback system compensates for the effect of pressure variations on fluid density and flow characteristics, maintaining measurement accuracy across substantial pressure ranges.
Solution Approach 2:
The patent modifies the operating parameters of the fluidic oscillator and detector to compensate for pressure effects. By adjusting the alternating driving signal parameters and detector sensitivity in response to pressure variations, the system maintains accurate flow measurements despite substantial pressure changes.
4Reliability
If alternating driving signal is applied to sensing electrodes, then electrode polarization is prevented, but additional signal processing is required to distinguish valid signals from noise
Solution Approach 1:
The patent applies an alternating driving signal at a specific frequency to the sensing electrodes, which creates a periodic response that can be easily distinguished from noise. This periodic action simplifies the signal processing requirements by providing a clear frequency reference for filtering and signal identification.
Solution Approach 2:
The patent uses feedback processing to analyze the signal characteristics and distinguish valid flow-induced signals from noise. The feedback mechanism continuously monitors the signal quality and adjusts processing parameters to maintain reliable measurements while managing the complexity of signal 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 solution ensures accurate and reliable fluid flow measurement by minimizing noise interference and distinguishing between valid and erroneous signals, maintaining accuracy over a large turn-down ratio and varying flow conditions.
Implementation Method 1
magnetic field generating means to apply a magnetic field across the flow path and at least one pair of sensing electrodes to detect the resulting e.m.f.
Implementation Method 2
a driving signal applicator which applies an alternating driving signal to the sensing electrodes to prevent polarization of the sensing electrodes in use
Implementation Method 3
the high velocity component of the fluid will 'attach' itself to the wall of one of the channels by the Coanda effect, but then as a result of the action of the fluid that is fed back, it will switch across to the other wall
Data Source
AI summary
A fluidic oscillator liquid flow meter comprising a body having an inlet portion to receive a flow of liquid to be measured, an outlet portion, a main channel defining a flow path between the inlet and outlet, the flow path including feedback structure to induce oscillations in the flowing fluid, the oscillations being detected by detector comprising means to apply a magnetic field across the flow path and sensing electrodes to detect the resulting e.m.f., the electrodes being positioned such that they protrude from the body into the flow path. A meter having driving signal means, which applies an alternating driving signal to the sensing electrodes, is also disclosed.