Bending Oscillator Density Correction Using Second Harmonic Damping
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Solution Overview
Problem
Existing methods for measuring fluid density using flexural resonators are hindered by viscosity-related errors, particularly at high viscosities, due to ambiguity in signal interpretation and the need for multiple harmonic evaluations, which complicates the correction process and reduces measurement accuracy.
Innovation Solution
The method employs a higher-order vibration mode, specifically the second harmonic, to determine damping parameters and correct viscosity-related density errors, allowing for more accurate and efficient viscosity measurements by analyzing the damping behavior of the second harmonic and using it to adjust the measured density values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first harmonic is used for viscosity correction, then the correction can be performed, but the signal becomes ambiguous in the relevant viscosity range and requires complex evaluation
Solution Approach 1:
The patent changes the harmonic parameter from the first harmonic to the second harmonic for viscosity correction measurements. This parameter change shifts the ambiguity region to higher viscosities, providing unambiguous signals in the relevant viscosity range (up to 30,000 mPas) and simplifying the evaluation process while maintaining correction accuracy.
2Measurement precision
If multiple harmonics are evaluated for viscosity correction, then correction accuracy can be improved, but the measurement time and complexity increase
Solution Approach 1:
The patent extracts and focuses solely on the second harmonic for viscosity correction, eliminating the need to evaluate multiple harmonics. This extraction approach provides sufficient correction accuracy for viscosities up to 30,000 mPas while significantly reducing measurement time and computational complexity compared to analyzing multiple harmonics.
3Ease of operation
If the fundamental frequency is used for density measurement, then the measurement is straightforward, but viscosity-related errors remain uncorrected
Solution Approach 1:
The patent segments the measurement process into two independent parts: (1) density measurement using the fundamental frequency, which remains simple and straightforward, and (2) viscosity correction using the second harmonic, which provides the necessary correction data. This segmentation allows both simplicity and accuracy to coexist by assigning different functions to different harmonics.
4Measurement precision
If higher-order vibration modes are used, then the ambiguity region shifts to high viscosities, but the vibration amplitude decreases
Solution Approach 1:
The patent changes the harmonic parameter to the second harmonic, which optimally balances vibration amplitude and viscosity range coverage. This parameter change shifts the ambiguity region to higher viscosities while maintaining sufficient vibration amplitudes for accurate measurements up to 30,000 mPas, avoiding the need to use higher-order modes that would produce excessively small amplitudes.
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 shifts the ambiguity region to high viscosities, enabling accurate viscosity corrections up to 30,000 mPas, simplifying the evaluation process and improving measurement accuracy by eliminating the need for multiple harmonic evaluations, thus enhancing the precision of fluid density measurements.
Implementation Method 1
The tube is excited electronically to oscillation or resonance oscillation. The natural frequency of the U-shaped tube is influenced only by that portion of the sample which is actually participating in the oscillation.
Implementation Method 2
A measuring instrument includes a structure capable of oscillating a flexural vibrator, which is constituted by a hollow, U-shaped, glass or metal tube. This tube is excited electronically to oscillation or resonance oscillation.
Implementation Method 3
stimulated for determining a damping parameter or viscosity value of the to be tested fluid of the bending transducer to the resonant vibration on the second or higher harmonic and at this resonant vibration of the damping parameters of the flexural resonator for the examined fluid
Data Source
AI summary
The invention relates to a method for determining a corrected value for the viscosity-dependent density of a fluid under investigation using a bending oscillator, wherein - a first adjustment table relating to the relationship between the density of standard fluids and the period of the bending oscillator for a resonant natural frequency, preferably the fundamental frequency, is provided, and - the bending oscillator is excited to this resonant natural frequency and, at this natural frequency, the period of the bending oscillator for the fluid under investigation and, via the period from the adjustment table, the associated density value for the fluid under investigation are determined.According to the invention, it is provided that - to determine a damping parameter or viscosity value of the fluid under investigation, the bending oscillator is excited to resonant vibration on the second or a higher harmonic, and during this resonant vibration, the damping parameter of the bending oscillator for the fluid under investigation or the viscosity value for the fluid under investigation assigned to this damping parameter in a second, provided adjustment table is determined, and - with the measured damping parameter or the obtained viscosity value, a correction is made with regard to the viscosity of the density value obtained during the measurement of the fluid under investigation at the resonant natural vibration.