Flowmeter Orifice Design for Pressure-Dependent Flow Distribution
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Solution Overview
Problem
Conventional flowmeters experience deviations in sensor output due to changes in fluid pressure, leading to inaccuracies in flow rate measurement, as the distribution ratio between sensor-side and bypass-side resistances is affected by fluid pressure, causing discrepancies between positive and negative fluid pressures.
Innovation Solution
A flowmeter design featuring a distribution orifice and a main orifice with similar changing trends in effective sectional area in response to fluid pressure changes, ensuring minimal deviation in the distribution ratio and maintaining accuracy across varying pressures, with the main orifice being nozzle-shaped and the distribution orifice having multiple holes to enhance pressure loss and contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional flowmeter uses a sensor passage and bypass passage with fixed resistance, then the structure is simple, but the distribution ratio changes with fluid pressure causing measurement inaccuracy
Solution Approach 1:
The patent applies parameter changes by making the effective sectional areas of both the main orifice and distribution orifice change in response to fluid pressure changes. Specifically, both orifices are designed so that their effective sectional areas decrease in the negative pressure region, maintaining a balanced distribution ratio. This resolves the contradiction by allowing the device to adapt to pressure changes while maintaining measurement accuracy.
Solution Approach 2:
The patent segments the flow path into multiple controlled sections: the main orifice in the bypass passage and the distribution orifice in the sensor passage. By independently designing the characteristics of each orifice, the system can balance their respective resistances to maintain a stable distribution ratio across different pressure conditions, thereby improving measurement precision without excessive complexity.
2Adaptability or versatility
If the flowmeter is designed to work with positive pressure fluids, then it performs well under positive pressure, but shows significant deviation when used with negative pressure fluids
Solution Approach 1:
The patent applies parameter changes by designing both the main orifice and distribution orifice to have effective sectional areas that change in response to fluid pressure. In the negative pressure region, both effective sectional areas decrease, which maintains the balance between sensor-side and bypass-side resistances. This allows the flowmeter to maintain consistent sensor output across both positive and negative pressure conditions, significantly improving adaptability while preserving measurement precision.
3Measurement precision
If the distribution orifice has a large effective sectional area, then the flow rate through the sensor passage is sufficient for accurate measurement, but the distribution ratio becomes sensitive to pressure changes
Solution Approach 1:
The patent applies parameter changes by designing the distribution orifice with multiple holes whose effective sectional area changes in response to pressure. In the negative pressure region, the effective sectional area decreases, which compensates for the increased ease of flow through the sensor passage. This maintains the distribution ratio stability while ensuring sufficient flow rate for accurate measurement across different pressure conditions.
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 flowmeter effectively prevents degradation in sensor output accuracy by stabilizing the distribution ratio, reducing deviations to about one-third compared to conventional designs, even under negative fluid pressure conditions, thereby enhancing measurement precision.
Implementation Method 1
a distribution orifice provided on an inlet side of the sensor passage and a main orifice provided in the bypass passage
Data Source
AI summary
A flowmeter including a sensor passage disposed with a sensor chip for measuring a flow rate and an orifice passage as a bypass passage placed with respect to the sensor passage is provided. The orifice passage has a passage diameter which is smaller than a passage diameter of an inflow passage, a distribution orifice is placed on an inlet side of the sensor passage, and the orifice passage and the distribution orifice are configured such that changing trends in an effective sectional area becomes same in a graph including a vertical axis indicating the effective sectional area and a lateral axis indicating a fluid pressure of a fluid.