Pitot Tube Vortex Stabilizer for Flow Measurement Accuracy
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Solution Overview
Problem
Averaging pitot tube-based flow sensors face inaccuracies in flow rate measurements due to unstable oscillations in differential pressure, particularly low-frequency oscillations that can be misinterpreted as changes in flow rate, leading to errors in fluid flow measurement.
Innovation Solution
The implementation of a vortex shedding stabilizer, combined with boundary layer fences and a downstream element, stabilizes low-frequency oscillations and enhances the coherence of vortex shedding, thereby improving the accuracy of flow measurements by reducing fluctuations in the differential pressure signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an averaging pitot tube is used to measure flow rate, then flow measurement capability is provided, but low-frequency oscillations in differential pressure cause measurement inaccuracies
Solution Approach 1:
A vortex shedding stabilizer is introduced as an intermediary component in the flow path upstream of the pitot tube. This stabilizer mediates the flow conditions by generating coherent vortex shedding that suppresses low-frequency oscillations in the differential pressure signal, thereby improving measurement reliability without sacrificing accuracy
Solution Approach 2:
The invention changes the flow regime parameters by introducing controlled vortex shedding through the stabilizer. This modifies the flow characteristics upstream of the measurement point, transforming unstable low-frequency oscillations into more predictable high-frequency vortex patterns that do not interfere with accurate flow rate determination
2Measurement precision
If the pitot tube body impedes fluid flow to create differential pressure, then flow measurement is enabled, but unstable vortex shedding causes signal variations
Solution Approach 1:
The vortex shedding stabilizer performs preliminary action on the flow upstream of the pitot tube. By pre-establishing coherent vortex patterns before the flow reaches the measurement device, the stabilizer ensures that the differential pressure signal reflects true flow rate variations rather than unstable vortex shedding, thereby improving signal quality
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 results in more accurate and repeatable flow measurements by minimizing the impact of low-frequency oscillations and ensuring consistent vortex shedding patterns, leading to improved reliability and precision in fluid flow monitoring.
Implementation Method 1
stabilizes low-frequency oscillations and enhances the coherence of vortex shedding
Implementation Method 2
boundary layer fences
Implementation Method 3
A pressure difference between the upstream side and the downstream side of the pitot tube is measured and correlated to flow rate
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A differential pressure flow measurement system (12) includes a pressure sensor (28) coupled to measurement circuitry (34). An elongate probe (20) is configured to be inserted into a conduit (18) which carries a flow of process fluid. The pressure sensor (28) senses a pressure difference in the fluid flow generated as the fluid flows past the probe (20). A vortex shedding stabilizer (80, 90) is positioned proximate the elongate probe (20) and in the flow of process fluid. The vortex shedding stabilizer (80, 90) is configured to stabilize vortex shedding in the flow of fluid proximate the elongate probe (20).