Gas-Charged Liquid Density Measurement via Resonant Frequency Correction
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Solution Overview
Problem
Existing methods for determining the physical parameters of gas-charged liquids, such as mass flow rate and density, suffer from cross-sensitivities to velocity of sound and compressibility, especially when the gas charge affects oscillatory behavior in measuring tubes, leading to inaccurate measurements and the suppression of certain oscillation modes.
Innovation Solution
A method involving a measuring transducer with a measuring tube that excites oscillations in a bending oscillation mode, identifies the suppressed excitation frequency as the resonant frequency of the gas-charged liquid, and uses this to calculate a density correction term and mass flow correction term, allowing for accurate determination of physical parameters by compensating for cross-sensitivities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow measurement is performed in two different modes (bending oscillation mode and radial mode), then compressibility compensation is achieved, but device complexity increases due to requiring more sensors and a more complex exciter structure
Solution Approach 1:
The patent extracts only the essential bending oscillation mode measurement from the dual-mode approach, eliminating the need for radial mode sensors and excitation mechanisms. The invention achieves compressibility compensation by measuring only the bending oscillation eigenfrequency and applying correction algorithms, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the measurement parameter from requiring two oscillation modes to using only the bending oscillation eigenfrequency. By focusing on a single mode and applying mathematical corrections for compressibility effects, the invention simplifies the device structure while achieving the same compensation goal.
2Measurement precision
If the resonant frequency of the oscillating gas-charged liquid lies close to the eigenfrequency of a bending oscillation mode, then the influence of the eigenfrequency on density measurement increases, but measurement accuracy deteriorates due to suppression of the bending oscillation mode
Solution Approach 1:
The patent implements feedback by continuously monitoring the eigenfrequency of the bending oscillation mode and using this information to correct density measurements. When the resonant frequency of the gas-charged liquid approaches the eigenfrequency, the system detects the frequency shift and applies appropriate corrections to maintain measurement accuracy despite mode suppression effects.
Solution Approach 2:
The patent treats the gas-charged liquid as a composite medium with distinct phases (gas bubbles and liquid), where the resonant frequency provides additional information about the mixture properties. By combining the eigenfrequency measurement with resonant frequency analysis, the system achieves accurate density measurement even when modes interact.
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 precise measurement of density and mass flow rate by correcting preliminary values using the resonant frequency, effectively addressing the limitations of previous methods and improving measurement accuracy even when oscillation modes are suppressed.
Implementation Method 1
the measuring tube is excitable between the two securement means to execute oscillations in at least one bending oscillation mode
Implementation Method 2
identifying the suppressed excitation frequency as the resonant frequency of the gas-charged liquid
Data Source
AI summary
A method for ascertaining a physical parameter of a liquid, which has a gas charge using a measuring transducer having a measuring tube for conveying the medium. The measuring tube executes oscillations in bending oscillation mode. The method includes: exciting the measuring tube with an eigenfrequency of a bending oscillation mode—or f1-mode, ascertaining a suppressed excitation frequency, at which the oscillation amplitude of the measuring tube is minimum; identifying the frequency as the resonant frequency of the gas-charged liquid; ascertaining a density correction term as a function of the resonant frequency for correcting a preliminary density measured value and/or mass flow correction term as a function of the resonant frequency for correcting a preliminary mass flow rate measured value, and/or ascertaining the velocity of sound in the gas-charged liquid in the measuring tube as a function of the resonant frequency.