Vortex Flow Meter Temperature Correction for Accurate Flow Rate
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Solution Overview
Problem
Conventional temperature sensor-integrated vortex flow meters lack a reliable mechanism to correct measurement errors due to fluid temperature variations, leading to inaccuracies in flow rate calculations.
Innovation Solution
A flow measurement device with a bluff body, sensing element, electric circuit, arithmetic circuit, and downstream temperature sensor, utilizing a correction table to adjust flow rates based on temperature and vortex shedding frequency relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Karman vortex flow meter is used to measure fluid flow rate, then the measurement has low pressure loss, fast response rate and simple structure, but the measurement accuracy deteriorates due to temperature variations affecting the Strouhal number
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual temperature of the fluid and using it to dynamically correct the Strouhal number in the flow rate calculation. The temperature measurement feedback loop allows the system to adjust the calculation parameters based on real-time conditions, thereby maintaining measurement accuracy despite temperature variations.
Solution Approach 2:
The patent applies parameter changes by adjusting the Strouhal number based on temperature measurements. Instead of using a fixed Strouhal number, the system modifies this critical parameter according to the actual fluid temperature, which directly compensates for the temperature-induced measurement errors and restores accuracy.
2Measurement precision
If temperature-based correction means is added to correct flow rate measurement errors, then the measurement accuracy improves, but the device complexity increases due to additional temperature sensor and correction mechanism
Solution Approach 1:
The patent merges the temperature sensing function with the existing flow measurement system by integrating a temperature sensor into the bluff body structure. This combination allows the temperature measurement to be performed at the same location where flow characteristics are measured, eliminating the need for separate temperature measurement components and reducing overall system complexity.
Solution Approach 2:
The bluff body is designed to serve multiple functions: it generates Karman vortices for flow measurement and simultaneously houses the temperature sensor for temperature measurement. This multi-functionality reduces the number of separate components needed in the system, thereby reducing device complexity while maintaining measurement accuracy.
3Measurement precision
If temperature sensor is integrated into the bluff body, then the temperature measurement accuracy improves, but the device complexity increases due to integration requirements
Solution Approach 1:
The temperature sensor is nested within the bluff body structure, with the sensor positioned inside the hollow interior of the bluff body. This nesting arrangement allows the temperature sensor to be thermally coupled with the fluid while being protected by the bluff body structure, achieving accurate temperature measurement without requiring separate housing or complex mounting arrangements.
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 device reliably corrects flow rate measurements by accounting for temperature-induced changes in vortex shedding frequency, ensuring accurate flow rate calculations regardless of fluid temperature.
Implementation Method 1
a sensing element for sensing a change in Karman vortices generated downstream of the bluff body by converting the change into an electrical signal
Implementation Method 2
When an obstacle is placed in a flow of a fluid, a regular pattern of alternating to vortices known as a Karman vortex street is generated downstream of the obstacle
Data Source
AI summary
A flow measurement device includes a bluff body in a flow path in a measuring pipe to generate Karman vortices downstream of the bluff body, and a temperature sensor downstream of a piezoelectric element for sensing a change in the Karman vortices by converting the change into an electrical signal. A flow rate of a fluid can be corrected based on a relation of a vortex shedding frequency at a temperature of the fluid measured with the temperature sensor and a vortex shedding frequency of the fluid measured at a reference temperature.