Laser Doppler Flowmeter Sensor Array for Pipe Bend Accuracy
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Solution Overview
Problem
Laser Doppler flowmeters face challenges in accurately measuring average flow velocity and flow rate in pipes with bends due to non-uniform velocity distributions caused by centrifugal forces and pressure gradients, leading to fluctuations in measurement data.
Innovation Solution
A fluid measurement device with multiple sensor elements arranged around the pipe, where each sensor has a light source unit and a light reception unit in proximity along the pipe axis, with a partition structure to prevent saturation from reflected light, and a calculation unit that processes signals to determine flow velocity and rate, utilizing forward-scattered light to enhance measurement accuracy and reduce the effect of pipe bends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor element is used in a laser Doppler flowmeter, then the device structure is simple and cost-effective, but measurement accuracy deteriorates in pipes with bends due to non-uniform velocity distributions
Solution Approach 1:
The patent divides a single sensor into multiple sensor elements (first sensor element, second sensor element, etc.) arranged around the pipe. Each sensor element independently measures flow velocity, and the calculation unit averages these measurements to obtain accurate flow velocity and flow rate even in pipes with bends, thereby resolving the contradiction between simple structure and measurement accuracy.
2Measurement precision
If the light source unit and light reception unit are placed far apart, then measurement accuracy improves by capturing more scattered light, but device size increases and signal intensity decreases
Solution Approach 1:
The patent merges the light source unit and light reception unit into a closely integrated sensor element structure. By placing them in proximity within each sensor element, the device maintains a compact size while achieving accurate measurement through the combined effect of multiple sensor elements arranged around the pipe.
3Measurement precision
If multiple sensor elements are arranged around the pipe, then measurement accuracy improves by averaging data, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent designs each sensor element with universal functionality, where both the light source unit and light reception unit serve multiple purposes across different sensor elements. This standardized multi-functional design reduces overall device complexity despite having multiple sensor elements, as each element follows the same structural pattern and can be manufactured using identical processes.
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 device achieves more accurate measurements of average flow velocity and flow rate by averaging data from multiple sensors, reducing the impact of pipe bends by 14% to 18% compared to conventional methods, while maintaining signal intensity through selective detection of forward-scattered light.
Implementation Method 1
When a scatterer contained in the fluid in the flow path and having a velocity passes through a region irradiated with the laser light, the laser light is scattered, and the frequency of the scattered light is subjected to the Doppler shift.
Implementation Method 2
a light reception unit receiving and photoelectrically converting the coherent light
Data Source
AI summary
A fluid measurement device includes sensor elements that are arranged around a pipe in which a fluid containing a scatterer flows and include each of a light source, a light receiver, and a partition structure for shading between the light source and the light receiver, a signal processor that processes the signals obtained from the light that has been received and photoelectrically converted by the light receivers, and a calculator that calculates at least one of a flow velocity and a flow rate using the signals processed by the signal process unit. The light source and the light receiver in each of the sensor elements are arranged in proximity along the pipe axis direction of the pipe so as to have a reverse positional relationship to the light source and the light receiver in the adjacent sensor elements.