Impeller Flowmeter Taper Sections for High Turn-Down Ratio
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Solution Overview
Problem
Existing impeller-type flowmeters have limited turn-down ratios, typically ranging from 5:1 to 15:1, making them less effective for measuring a wide range of fluid flow rates, especially low flow rates, and often require specific installation conditions to ensure laminar flow.
Innovation Solution
The design features an impeller-type inline flowmeter with a significantly improved turn-down ratio of at least 30:1, incorporating an inlet flow taper section and an outlet flow taper section to manage fluid flow, allowing for measurement of low flow rates and high flow rates, and ensuring laminar flow without the need for a straight pipe leading up to the flowmeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional impeller-type flowmeters are used, then the structure is simple, but the turn-down ratio is limited to 5:1 to 15:1
Solution Approach 1:
The flow path is segmented into three distinct sections: inlet flow taper section, measurement chamber, and outlet flow taper section. Each section has a specific function - the inlet section conditions the flow, the measurement chamber houses the impeller, and the outlet section restores the flow. This segmentation enables the complex flow control needed for high turn-down ratio while keeping each individual section relatively simple in design.
Solution Approach 2:
The patent transitions from a conventional circular cross-sectional flow path to a non-circular cross-section in the measurement chamber. This dimensional change allows for optimized flow distribution around the impeller blades, improving measurement accuracy across a wider range of flow rates and enabling the high turn-down ratio of 30:1 or greater.
2Reliability
If conventional flowmeters are installed in pipes with varying flow patterns, then installation is flexible, but laminar flow cannot be ensured without straight pipe requirements
Solution Approach 1:
The inlet flow taper section performs preliminary flow conditioning before the fluid reaches the measurement chamber. The tapered geometry gradually adjusts the flow pattern, straightening streamlines and reducing turbulence. This preliminary action ensures laminar flow enters the measurement chamber regardless of the upstream plumbing configuration, eliminating the need for long straight pipe sections before installation.
Solution Approach 2:
The inlet flow taper section acts as an intermediary between the upstream pipe and the measurement chamber. It mediates the transition from potentially turbulent flow in the pipe to laminar flow required for accurate measurement, isolating the measurement chamber from disturbances in the upstream plumbing system.
3Measurement precision
If the flow path cross-sectional area is reduced to increase flow velocity, then measurement sensitivity improves, but flow restrictions increase
Solution Approach 1:
The flow path cross-sectional area is varied locally along the flow direction. The inlet section has a larger area that gradually tapers to a smaller area at the measurement chamber, then expands again in the outlet section. This local variation optimizes flow velocity at the impeller for sensitive measurement while the larger upstream and downstream areas minimize energy losses from flow restriction.
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 can accurately measure flow rates from as low as 0.1 ft/sec to as high as 12 ft/sec, achieving a turn-down ratio of up to 80:1, enabling effective leak detection and simplifying installation by ensuring laminar flow regardless of the plumbing system configuration.
Implementation Method 1
The cross-sectional flow area within the inlet flow taper section continuously decreases between the inlet of the inlet flow taper section and the outlet of the inlet flow taper section
Implementation Method 2
The cross-sectional flow area within the outlet flow taper section continuously increases between the inlet of the outlet flow taper section and the outlet of the outlet flow taper section
Implementation Method 3
an impeller positioned at least partially within the measurement chamber and having a plurality of impeller blades
Implementation Method 4
The rate at which the impeller turns may be measured and used to determine the fluid flow rate through the pipe
Data Source
AI summary
An in-line, impeller type flowmeter having an inlet flow taper section to converge flow to a measurement chamber and an outlet flow taper section after the measurement chamber, and further exhibiting a high turn-down ratio above about 30:1, and being suitable for use with a pipe having a nominal inner diameter no greater than one inch.