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Volumetric imaging of flame refractive index, density, and temperature using background-oriented Schlieren tomography

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Science China(Technological Sciences) 2021年第1期64卷 98-110页

作者： LIU HeCong HUANG JianQing LI Lei CAI WeiWei School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Volumetric imaging represents one of the major development trends of flow diagnostics due to both the advancement in hardware and the requirement for more information to further understand complicated turbulent and/or reactive flows. Backgroundoriented Schlieren tomography(BOST) has become increasingly popular due to its experimental simplicity. It has been demonstrated to be capable of simultaneously recovering the distributions of refractive index, density, and temperature of ***, its capability in thermometry has only been demonstrated under the axisymmetric assumption, which greatly limits its applicability. In this work, we dedicated to developing a cost-effective BOST system for the simultaneous retrieval of refractive index, density, and temperature distributions for the asymmetric flame. A few representative tomographic inversion algorithms were assessed as well. Both numerical and experimental demonstrations were conducted and the results show that our implemented BOST can successfully reconstruct the three-dimensional temperature distribution with a satisfactory accuracy.

关键词： Schlieren tomography combustion diagnostics temperature

Tomography system for measurement of gas properties in combustion flow field

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Chinese Journal of Aeronautics 2017年第5期30卷 1697-1707页

作者： Junling SONG Yanji HONG Mingyuan XIN Guangyu WANG Zhaoran LIU State Key Laboratory of Laser Propulsion & Application Space Engineering University Beijing 101416 China Science and Technology on Scramjet Laboratory Hypervelocity Aerodynamics Institute CARDC Mianyang 621000 China

This paper describes a self-designed fiber-coupled tomography system and its application in combustion diagnostics. The tomographic technique, which combines tunable diode laser spectroscopy and algebraic reconstruction technique, enables the simultaneous reconstruction of temperature and gas concentration with both spatial and temporal resolutions. The system measures a maximum diameter of 35 cm in a circular area with a minimum spatial resolution of 1 mm×1 mm and temporal response of up to 1 kHz. Simulations validate the effects of the beam arrangement and discrete grid on reconstruction accuracy, and give the optimal beam arrangements. Experiments are made to demonstrate the tomography method, and systems are constructed in laboratory and on engineering test benches.

关键词： Absorption combustion diagnostics Spectroscopy Temperature Tomographic image

Challenges and perspectives of combustion chemistry research

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Science China Chemistry 2017年第11期60卷 1391-1401页

作者： Wenhao Yuan Yuyang Li Fei Qi Key Laboratory for Power Machinery and Engineering of Ministry of Education Shanghai Jiao Tong UniversityShanghai 200240China

In the past decades, combustion chemistry research grew rapidly due to the development of combustion diagnostic methods,quantum chemistry methods, kinetic theory, and computational techniques. A lot of kinetic models have been developed for fuels from hydrogen to transportation fuel surrogates. Besides, multi-scale research method has been widely adopted to develop comprehensive models, which are expected to cover combustion conditions in real combustion devices. However, critical gaps still remain between the laboratory research and real engine application due to the insufficient research work on high pressure and low temperature combustion chemistry. Besides, there is also a great need of predictive pollutant formation model. Further development of combustion chemistry research depends on a closer interaction of combustion diagnostics, theoretical calculation and kinetic model development. This paper summarizes the recent progress in combustion chemistry research briefly and outlines the challenges and perspectives.

关键词： combustion chemistry combustion diagnostics validation experiments quantum chemistry calculation rate constant calculation kinetic model

Measurements of flame temperature by femtosecond CARS

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Chinese Optics Letters 2012年第B06期10卷 208-209页

作者：夏元钦赵阳张天天贺平樊荣伟董志伟陈德应张中华 National Key Laboratory of Tunable Laser Technology Harbin Institute of Technology Harbin 150080 China

Time-resolved femtosecond coherent anti-Stokes Raman spectroscopy （fs-CARS） is utilized to measure the methane/oxygen/nitrogen flame temperature at atmospheric-pressure. The measurements are performed using the CARS signal of N2 with 40-fs laser pulses in the first few picoseconds after the initial in-phase excitation. Flame temperatures at 300 and 1 325 K are measured, the experimental results show good agreements with theoretical ones and present a good repeatability.

关键词： 300.6230 Spectroscopy, coherent anti-Stokes Raman scattering 300.6530 Spectroscopy, ultrafast 320.7150 Ultrafast spectroscopy 280.1740 combustion diagnostics