Flow Laminator Rod Geometry for Stable Mass Flow Sensing
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Solution Overview
Problem
Existing fluid sensing apparatuses in mass flow controllers face challenges in accurately measuring flow rates due to turbulence in the flow passage, which can lead to noise and variability in the sensed pressure, especially in devices using simple orifice-type flow restrictions.
Innovation Solution
A fluid sensing apparatus with a laminar flow element comprising a flow stabilization rod that extends along the fluid flow channel from upstream to downstream of the flow restriction, reducing the hydraulic diameter and promoting laminar flow, thereby reducing turbulence and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple orifice-type flow restriction is used, then the device complexity is reduced, but turbulence occurs causing noise and variability in sensed pressure
Solution Approach 1:
A flow stabilisation rod is introduced as an intermediary element within the flow channel. The rod extends from the upstream side to the downstream side of the orifice, acting as a mediator that stabilizes the fluid flow without requiring complex external components. This simple intermediary structure effectively reduces turbulence and improves measurement precision while maintaining device simplicity
Solution Approach 2:
The flow channel is segmented by the flow stabilisation rod, which divides the flow path into distinct regions. The rod creates a controlled flow pattern by segmenting the fluid stream as it passes through the orifice, reducing chaotic turbulence while maintaining the simplicity of the orifice-type restriction
2Measurement precision
If a laminar flow element is added downstream of the flow restriction, then turbulence is reduced and measurement accuracy is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The flow stabilisation rod is merged with the existing flow channel structure, integrating the turbulence reduction function directly into the flow path rather than adding a separate downstream laminar flow element. This merging approach achieves laminar flow conditions without increasing device complexity or manufacturing cost
Solution Approach 2:
Instead of adding a complex downstream laminar flow element, the solution introduces a simple rod extending in the longitudinal dimension of the flow channel. This dimensional approach stabilizes flow by occupying the central flow region, achieving measurement precision improvement without increasing overall device complexity
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 arrangement enhances the accuracy of flow measurement by encouraging laminar flow and reducing noise and variability in fluid flow characteristics, making it suitable for applications in mass flow control and other fluid sensing applications.
Implementation Method 1
a laminar flow element comprising a flow stabilisation rod extending along the fluid flow channel at least from the first location to the second location
Implementation Method 2
the flow restriction comprises a reduction in the hydraulic diameter of the fluid sensing portion of the fluid flow channel
Data Source
AI summary
A fluid sensing apparatus is provided having a fluid flow channel having a flow restriction. A fluid sensor is in fluid communication with first and second fluid ports, and a laminar flow element. The laminar flow element includes a flow stabilisation rod which defines a fluid sensing portion of the fluid flow channel. The flow restriction comprises a reduction in the hydraulic diameter of the fluid sensing portion of the fluid flow channel which is caused by a decrease in diameter of the fluid flow channel, or by an increase in the diameter of the flow stabilisation rod, or by both a decrease in diameter of the fluid flow channel and an increase in the diameter of the flow stabilisation rod. Also provided is a mass flow controller including such a fluid sensing apparatus.