Multi-Lightpath Gas Measurement Apparatus for Combustion Flow Field
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Solution Overview
Problem
Conventional combustion flow field measurement techniques are invasive, costly, and limited in accuracy and speed, while existing tunable diode laser absorption spectroscopy (TDLAS) methods only provide average gas parameter values along a single lightpath, failing to capture the two-dimensional distribution of gas parameters due to flow mixing and gradient changes.
Innovation Solution
A multi-lightpath and multi-angle measurement apparatus using an electrically controlled rotary table and electronically controlled translation tables, combined with an all-fiber coupling structure and detector array, enables synchronous data acquisition from 16 lightpaths, allowing for two-dimensional reconstruction of gas parameters in combustion flow fields with limited space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact measurement means (pneumatic velocity probe, gas sampling probe, thermocouple temperature probe) are used, then measurement can be performed, but maintenance cost increases, failure rate increases, response speed decreases, and carrying and mounting becomes inconvenient
Solution Approach 1:
The patent replaces mechanical contact measurement probes with optical measurement systems (laser transmitters and detectors) that measure combustion flow field parameters without physical contact. This substitution eliminates the mechanical wear and failure issues of conventional probes while maintaining measurement capability through optical absorption spectroscopy.
Solution Approach 2:
The patent introduces laser beams as an intermediary medium to transfer measurement information from the combustion flow field to detectors. The laser light passes through the flow field and carries absorption information, serving as a non-contact intermediary that avoids direct mechanical interaction with the harsh combustion environment.
2Measurement precision
If intrusive probes are used for measurement, then measurement data can be obtained, but the measured flow field is destructed, shock waves are generated, and air flow is interfered with, affecting measurement accuracy
Solution Approach 1:
The patent replaces intrusive mechanical probes with non-contact optical measurement systems. Laser beams pass through the combustion flow field without physically disturbing it, eliminating shock wave generation and flow field destruction while maintaining high measurement accuracy through absorption spectroscopy.
3Loss of information
If TDLAS line-of-sight measurement is used, then average gas parameter value in lightpath direction can be obtained, but spatial distribution information is lost and two-dimensional reconstruction requirement cannot be met
Solution Approach 1:
The patent segments the single line-of-sight measurement into multiple lightpaths arranged in arrays (horizontal and vertical). By dividing the measurement into multiple discrete beams that sample different regions of the flow field, spatial distribution information is recovered while maintaining the simplicity of TDLAS technology.
Solution Approach 2:
The patent transitions from one-dimensional line-of-sight measurement to two-dimensional spatial mapping by arranging laser beams in horizontal and vertical arrays. This dimensional expansion allows reconstruction of gas parameter distributions across the flow field cross-section while using the same fundamental TDLAS measurement principle.
4Measurement precision
If multiple lightpaths and multi-angle measurement are implemented, then two-dimensional reconstruction accuracy improves, but measurement apparatus structure becomes more complex and measurement space requirement increases
Solution Approach 1:
The patent merges multiple laser transmitters and detectors into compact arrays with shared optical components and control systems. By combining measurement functions into integrated modules, the system achieves multi-lightpath capability while minimizing the physical space required for the measurement apparatus.
Solution Approach 2:
The patent designs measurement apparatus with universal, multi-functional components that can perform multiple measurement functions. The laser array system can simultaneously execute multiple lightpaths and reconstruction algorithms, reducing the overall space requirement by eliminating dedicated hardware for each function.
5Measurement precision
If data from dozens of lightpaths are acquired, then two-dimensional measurement capability is achieved, but data amount becomes huge and processing requirements increase
Solution Approach 1:
The patent implements preliminary organization and pre-processing of data from multiple lightpaths during acquisition. By structuring the data flow and applying preliminary processing steps as data is collected, the system reduces the burden on final reconstruction algorithms and accelerates overall processing time.
Solution Approach 2:
The patent employs feedback mechanisms in the data processing pipeline where intermediate processing results inform subsequent processing steps. The reconstruction algorithm uses feedback from partial reconstructions and error analysis to optimize processing efficiency and reduce total computation time while maintaining accuracy.
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 apparatus achieves high accuracy and efficiency in two-dimensional measurement of gas temperature and component concentration, reducing reconstruction errors and saving space, with a compact and versatile design suitable for various combustion flow fields.
Implementation Method 1
a laser beam is projected through the measured area
Implementation Method 2
a detector array...converts light signals into electrical signals
Data Source
AI summary
The present invention discloses a multi-lightpath and multi-angle measurement apparatus, including an electrically controlled rotary table, electronically controlled translation tables, a laser transmitting/receiving end face, laser couplers, a multipath data acquisition card, a laser controller, a translation controller, an etalon, a laser, detectors, and a computer. The measurement apparatus uses an all-fiber coupling structure, and two ends of the laser transmitting/receiving end face are respectively fixed on two electronically controlled translation tables. Therefore, a maximum area measured by the apparatus is 350 mm×350 mm, and an adjustable minimum translation distance is 1 mm. Bottoms of the translation tables are fixed on the electrically controlled rotary table. Featuring an ingenious design and a compact structure, the whole apparatus is easy to disassemble and easy to operate. The apparatus has high universality, and can implement two-dimensional measurement in a high-temperature combustion flow field.