Vortex Flowmeter Low-Flow Measurement via Differential Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vortex flowmeters have a minimum velocity limit for measuring flow rates, leading to inaccuracies and failure to register low flow rates, particularly in batch processes, due to their reliance on vortex shedding principles.
Innovation Solution
A vortex flowmeter that incorporates a bluff body and sensors to detect differential pressure, allowing for flow rate calculation using both vortex frequency and differential pressure measurements, even at low velocities below the conventional limit, thereby extending the measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vortex flowmeter uses the vortex shedding principle to measure flow rate, then it can provide reliable measurement at normal flow rates, but it fails to measure low flow rates below the minimum velocity limit
Solution Approach 1:
The patent combines two different measurement principles (vortex shedding and differential pressure measurement) into a single flowmeter device. The vortex sensor detects vortices for normal flow rates, while the differential pressure sensor measures pressure drop across the bluff body for low flow rates, allowing the device to operate across a wider range of flow conditions.
Solution Approach 2:
The patent changes the measurement parameter based on flow rate conditions. At normal flow rates, it uses vortex shedding frequency (which requires minimum velocity), while at low flow rates below the minimum velocity limit, it switches to differential pressure measurement, thereby extending the measurable range down to lower velocities.
2Adaptability or versatility
If a vortex flowmeter operates at low velocities below the conventional limit, then it can potentially measure low flow rates, but the vortex shedding principle no longer provides reliable measurements
Solution Approach 1:
The patent introduces a differential pressure sensor as an intermediary measurement mechanism that becomes active when the primary vortex shedding mechanism fails at low velocities. This intermediary sensor reliably measures low flow rates by detecting the pressure drop across the bluff body, compensating for the unreliability of vortex shedding at low Reynolds numbers.
3Productivity
If a vortex flowmeter is designed with a bluff body for vortex shedding, then it can measure flow rates effectively, but it cannot accurately measure flow rates at very low velocities
Solution Approach 1:
The bluff body serves multiple functions: it generates vortices for normal flow rate measurement and simultaneously creates a measurable pressure drop for low flow rate measurement. The flowmeter becomes multi-functional, using the same bluff body structure for both vortex shedding and differential pressure measurement purposes across different flow ranges.
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
Enables accurate flow rate measurement across a wider range of conditions, including low flow rates, with an error percentage of less than 10%, by utilizing differential pressure signals when vortex frequency is below the cutoff threshold.
Implementation Method 1
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
Data Source
Figure 1
Figure 2
Figure 3
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.