Vibratory Flowmeter Strain-Gage Detection of Undesired Modes
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Solution Overview
Problem
Existing vibrating flowmeters, such as Coriolis flowmeters, face issues with undesirable mode excitation that can interfere with accurate fluid flow measurement and potentially damage the meter, due to undetectable vibrations in unintended modes.
Innovation Solution
Incorporation of strain gages to detect strain changes and frequency shifts in the flowmeter's sensor assembly, connected in series with the drive mechanism, allowing the meter electronics to identify and alert or diagnose issues related to non-drive-mode frequencies, providing diagnostic information for calibration or condition adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gages are added to detect non-drive-mode vibrations, then measurement precision and reliability improve, but device complexity increases
Solution Approach 1:
The strain gages are integrated into the existing sensor assembly structure, allowing the same component to serve both as a structural element and as a sensing element for detecting undesirable mode excitation, thereby minimizing additional complexity
Solution Approach 2:
The strain gages are combined with the drive mechanism and sensor assembly components, merging multiple functions (driving and sensing) into a unified structure rather than adding separate independent systems
2Ease of operation
If strain gages are connected in series with the drive mechanism, then ease of operation improves through simplified wiring, but reliability may worsen due to single point of failure
Solution Approach 1:
The series connection enables the meter electronics to receive feedback signals from the strain gages that indicate when undesirable mode excitation occurs, allowing the system to monitor and respond to vibration conditions in real-time
3Reliability
If real-time monitoring of non-drive-mode frequencies is implemented, then reliability improves by preventing damage, but use of energy increases
Solution Approach 1:
The monitoring system operates by detecting frequency content in the strain gage signals, which can be performed periodically or event-triggered rather than requiring continuous high-energy processing, thus reducing overall energy consumption while maintaining protective functionality
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
Enhances the reliability and accuracy of flow measurements by detecting and preventing undesirable mode excitation, thereby stabilizing meter zero and preventing potential damage, through real-time monitoring and alerts.
Implementation Method 1
At least one strain gage is coupled to the sensor assembly, wherein the at least one strain gage is configured to detect a strain in the sensor assembly
Implementation Method 2
Each fluid tube is driven to oscillate at resonance in one of these natural modes
Implementation Method 3
A driver, such as a voice-coil style driver, applies a force to the one or more fluid tubes. The force causes the one or more fluid tubes to oscillate
Implementation Method 4
A pair of pickoff sensors is coupled to the one or more flow tubes, and configured to measure a vibrational response of the flow tubes induced by the drive mechanism
Data Source
AI summary
A flowmeter is provided that includes a sensor assembly (10) and a meter electronics (20). The flowmeter further has one or more flow tubes (130, 130’) and a drive mechanism (180) coupled to the flow tubes (130, 130’) and oriented to induce a drive mode vibration therein. A pair of pickoff sensors (170L, 170R) is coupled to the flow tubes (130, 130’), and is configured to measure a vibrational response induced by the drive mechanism (180). At least one strain gage (200A, 200B) is coupled to the sensor assembly (10), and configured to detect a strain in the sensor assembly (10). The meter electronics (20) is connected to the drive mechanism (180) and the strain gage (200A, 200B) in series. The meter electronics (20) is configured to detect frequencies at which changes in strain are occurring.