Optical Flow Measurement via Scattered Light Detection
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Solution Overview
Problem
Current optical fluid flow measurement technologies face challenges in accurately measuring local velocity profiles and flow rates of liquids and gases, particularly in laminar, turbulent, and intermediate flow regimes, especially for multi-phase fluids, as they often require invasive methods and struggle with spatial and temporal heterogeneity.
Innovation Solution
An optical method and apparatus that emit a light beam into a pipe to illuminate the fluid, using a light detector array outside the beam's field of view to detect scattered light, dividing the field of view into layers to determine instantaneous flow velocities, allowing for accurate measurement of velocity profiles, mass, and volume flow rates, applicable to laminar, turbulent, and intermediate flow regimes, including multi-phase fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single continuous wave light source and multiplicity of light detectors are used outside the pipe, then the measurement can be performed non-invasively, but the device complexity increases due to the need for precise alignment of beam and detector array
Solution Approach 1:
The patent uses a virtual copy of the physical pipe geometry created through optical scanning. The light source and detector array map the internal geometry of the pipe by detecting scattered light from particles, creating a virtual model that can be analyzed without physical intrusion. This copying approach maintains non-invasive measurement while reducing alignment complexity by working with the virtual model rather than requiring precise physical alignment.
Solution Approach 2:
The patent transforms the measurement parameters from direct velocity measurement to optical path analysis. By measuring the time of flight of light scattered by particles and analyzing the geometric parameters of the pipe cross-section, the system derives flow velocity indirectly. This parameter transformation simplifies the alignment requirements while maintaining measurement accuracy.
2Measurement precision
If the light beam illuminates the flow through a window in the pipe, then the measurement volume can be defined, but the measurement precision decreases for multi-phase fluids with spatial and temporal heterogeneity
Solution Approach 1:
The patent divides the pipe cross-section into multiple measurement zones by using a detector array that captures scattered light from different spatial locations. Each detector element corresponds to a specific region in the pipe cross-section, enabling independent velocity measurement for each zone. This segmentation allows the system to handle multi-phase flows with spatial heterogeneity by measuring velocity profiles across different layers and phases separately.
Solution Approach 2:
The patent transitions from one-dimensional point measurement to two-dimensional cross-sectional mapping. By arranging detectors in an array and using a light sheet to illuminate the entire cross-section, the system captures velocity information across the full pipe diameter simultaneously. This dimensional expansion enables accurate measurement of velocity profiles in multi-phase flows where different phases may have different velocity distributions across the cross-section.
3Measurement precision
If invasive measurement methods are used, then the measurement precision can be improved, but the reliability decreases due to potential flow disturbance
Solution Approach 1:
The patent replaces mechanical/invasive measurement probes with an optical measurement system. Instead of inserting physical sensors into the flow that could disturb the flow regime, the system uses light scattering from particles already present in the flow. This substitution maintains measurement precision while preserving flow stability and reliability, as the optical fields do not mechanically interact with the fluid.
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
Provides high accuracy and non-invasive in-line measurements of local velocity profiles, mass, and volume flow rates for liquids and gases, capable of handling complex flow regimes and multi-phase fluids, with the ability to derive changes in fluid viscosity and density over time.
Implementation Method 1
detect light caused by scattering of the beam with particles found in the fluid
Data Source
AI summary
A method of fluid flow measurement includes a emitting a light beam into a pipe through which a fluid flows, the light beam illuminating the fluid flowing in the pipe, using a light detector array to detect light caused by scattering of the beam with particles found in the fluid, the light beam being outside a field of view of the light detector array, dividing the field of view of the light detector array into layers, and determining an instantaneous flow velocity in each of the layers as a function of signals transmitted from the light detector array in each of the layers.