Vortex Flowmeter With Differential Pressure for Low-Flow Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vortex flowmeters have a minimum velocity limit for measuring flow rates due to the principle of vortex shedding, leading to inaccuracies in flow measurement, particularly in fluid batch processes where low flow rates are not registered.
Innovation Solution
A vortex flowmeter with integrated differential pressure sensing, using a bluff body to generate vortices and detect pressure differentials, allowing flow rate calculation even at low velocities below the conventional limit by combining vortex frequency and differential pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vortex shedding principle is used for flow measurement, then flow rate can be measured based on vortex frequency, but measurement is impossible at low velocities below the minimum Reynolds number limit
Solution Approach 1:
The patent combines two measurement principles: vortex shedding frequency measurement and differential pressure measurement. The differential pressure sensor measures pressure difference across the bluff body, which remains proportional to flow rate even at low velocities where vortex shedding cannot be detected. This merging allows the flowmeter to measure across the entire flow range from very low to high velocities.
Solution Approach 2:
The differential pressure sensor acts as an intermediary measurement mechanism that bridges the gap at low flow rates. When vortex shedding frequency is too low to be detected (below minimum Reynolds number), the differential pressure signal serves as the primary measurement signal, maintaining measurement capability where the vortex shedding principle alone would fail.
2Device complexity
If conventional vortex flowmeter design is used, then structure is simple, but measurement accuracy deteriorates at low flow rates due to minimum velocity limit
Solution Approach 1:
The bluff body serves multiple functions: it generates vortices for vortex shedding measurement at high flow rates, and simultaneously creates a measurable differential pressure at low flow rates. The differential pressure sensor adds measurement capability without requiring a separate flow restriction element, making the device multi-functional across different flow regimes.
3Adaptability or versatility
If differential pressure sensing is added to vortex flowmeter, then measurement range is extended to low velocities, but device complexity increases
Solution Approach 1:
The differential pressure sensing is merged with the existing vortex shedding measurement system. The bluff body that generates vortices also creates the differential pressure field, and the same processing electronics can handle both vortex frequency signals and differential pressure signals, reducing the need for separate dedicated systems.
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
Extends the measurement range of vortex flowmeters to include low flow rates, providing accurate flow rate measurements with an error percentage of less than 10% across a wide range of flow conditions, including Reynolds numbers below 2000.
Implementation Method 1
a vortex flowmeter, which measures flow rate based on the principle of vortex shedding. Vortex shedding refers to a natural process in which a fluid passing a bluff body (sometimes referred to as a shedder) causes a boundary layer of slowly moving fluid to be formed along the surface of the bluff body. A low pressure area is created behind the bluff body and causes the boundary layer to roll up, which generates vortices in succession on opposite sides of the bluff body.
Implementation Method 2
A pressure sensor arrangement is configured to detect a differential pressure in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of at least a portion of the bluff body and generate a differential pressure signal representing the differential pressure.
Data Source
AI summary
A vortex flowmeter for measuring a flow rate of a fluid. The meter includes a flowtube, a bluff body, and a vortex sensor. The bluff body, which is positioned in the flowtube, sheds vortices in the fluid when the fluid flows through the flowtube and the vortex sensor detects the vortices and generates a vortex signal representing the detected vortices. A pressure sensor arrangement is configured to detect a differential pressure in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of at least a portion of the bluff body and generate a differential pressure signal representing the pressure differential between the two locations. The flowmeter determines the fluid flow rate based on the pressure differential.