Visualization of Steam Addition Effect on OH Distribution in a Flame by Isotope Shift/Planar Laser-Induced Fluorescence (IS/PLIF) Spectroscopy

2004 ◽  
Vol 128 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Atsushi Katoh ◽  
Masahisa Shinoda ◽  
Kuniyuki Kitagawa ◽  
Ashwani K. Gupta
Keyword(s):  
Isotope Shift ◽  
Equivalence Ratio ◽  
Total Concentration ◽  
Combustion Process ◽  
Laser Induced Fluorescence ◽  
Oh Radicals ◽  
Percentage Increase ◽  
Dissociation Reaction ◽  
Planar Laser Induced Fluorescence ◽  
Planar Laser

Addition of steam to a flame has important implications in the combustion process. The dissociation of the added steam (e.g., H2O↔H+OH, etc.) is one of the effects that contribute to the production of radical species, such as OH, H, and O, in the flame. In order to distinctly visualize two types of OH radicals produced from the fuel-air combustion reaction and that from the dissociation reaction with the added steam, we have developed a new method for planar laser-induced fluorescence spectroscopy in combination with isotope shift (herein called IS/PLIF spectroscopy). This technique has been applied to examine a methane-oxygen-nitrogen premixed flame. Two-dimensional fluorescence intensity distributions of OH radicals in the flames were monitored under three different conditions. They include without steam addition, with H2O steam addition, and with D2O steam addition. From the experimental data obtained under the three conditions, the distinction between the two types of OH radicals could be obtained. The results showed that steam addition reduced the total concentration of OH produced from the combustion and dissociation reactions and that the dissociation reaction of the added steam contributed to the production of OH. Furthermore, the results indicated that the percentage decrease in OH from fuel-air combustion reactions due to the temperature decrease effect with steam addition was almost independent of the equivalence ratio during combustion. In contrast, the percentage increase in OH produced from dissociation reaction with the steam depended on the equivalence ratio.

Analysis of flame structure by isotope shift-planar laser induced fluorescence spectrometry of trace OH and OD Radicals

2013 ◽  
Vol 106 ◽  
pp. 334-339 ◽  
Author(s):  
Tsuyoshi Kajimoto ◽  
Eisuke Yamada ◽  
Masahisa Shinoda ◽  
Nelfa Desmira ◽  
Kuniyuki Kitagawa ◽  
...  
Keyword(s):  
Isotope Shift ◽  
Flame Structure ◽  
Laser Induced Fluorescence ◽  
Fluorescence Spectrometry ◽  
Planar Laser Induced Fluorescence ◽  
Planar Laser

Flame Imaging of Highly Turbulent Premixed Methane-Air Combustion Using Planar Laser Induced Fluorescence (PLIF) of CH (C-X)

2019 ◽  
Author(s):  
Md. Amzad Hossain ◽  
Md Nawshad Arslan Islam ◽  
Ahsan Choudhuri
Keyword(s):  
Equivalence Ratio ◽  
High Reynolds Number ◽  
Laser Induced Fluorescence ◽  
Experimental Methodology ◽  
Flame Dynamics ◽  
Planar Laser Induced Fluorescence ◽  
X Band ◽  
Planar Laser ◽  
High Reynolds ◽  
Flame Imaging

Abstract The article presents an investigation of CH (C-X) planar laser induced fluorescence imaging (PLIF) of highly turbulent methane-air flames inside a windowed combustor. Flame dynamics and flame growth and evolution of methane-air flames stabilized over a backward facing step at high Reynolds Number (Re) (Re = 15000 and Re = 30000) with an equivalence ratio of 0.7 are discussed. It was observed that the flame evolution was faster at Re = 30000 than that of Re = 15000. The rate of initiation or formation of wrinkles, detachment of the wrinkles and burnout of the burned gases from the flame core increased with the increase in Re. The qualitative flame imaging shows that the width of the flame profile increases as the flame progress towards downstream and the flame becomes thinner as the turbulence level increases. An experimental methodology was developed to optimize the system for excitation, detection of the CH C-X band and post-processing the PLIF images.

scholarly journals Investigation of Flame Evolution in Heavy Oil Boiler Bench Using High-Speed Planar Laser-Induced Fluorescence Imaging

2018 ◽  
Vol 8 (9) ◽  
pp. 1691 ◽  
Author(s):  
Jiangbo Peng ◽  
Zhen Cao ◽  
Xin Yu ◽  
Yang Yu ◽  
Guang Chang ◽  
...  
Keyword(s):  
Heavy Oil ◽  
High Speed ◽  
Combustion Process ◽  
Laser Induced Fluorescence ◽  
Bench Test ◽  
Planar Laser Induced Fluorescence ◽  
Planar Laser ◽  
Wrinkled Structure ◽  
Good Agreement

Over recent years, much attention has been paid to the performance evaluation of industrial-type burners. The ignition and stable combustion process are of great significance in assessing the quality of burner. The planar laser-induced fluorescence (PLIF) technique can be applied to heavy oil boilers, extending this technique to engineering applications. Considering the complex environment of the bench test, measures such as temperature control and moisture proofing are made to improve the possibility of detection using PLIF. In this paper, an experimental investigation of flame growth following ignition is reported. A wrinkled structure could be observed from the configuration of the ignition flame; its trajectory will be depicted. The results showed that the wrinkled structure developed downward, i.e., by deviation from the direction of the airflow. The displacement velocity of the flame was used to describe the combustion rate. Good agreement was obtained for the flame shapes of both forced ignition and autoignition. In addition, the center of combustion deviated from the center of boiler, possibly due to some irregularity in the burner’s assembly which was critical to the design of the combustion chamber.

scholarly journals Spatially resolved measurement of hydroxyl (OH) radical concentration in a microwave plasma jet by planar laser-induced fluorescence

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Jan Voráč ◽  
Jaroslav Hnilica ◽  
Vít Kudrle ◽  
Pavel Dvořák
Keyword(s):  
Microwave Plasma ◽  
Plasma Jet ◽  
Laser Induced Fluorescence ◽  
Oh Radicals ◽  
Oh Radical ◽  
Maximal Concentration ◽  
Spatially Resolved ◽  
Radical Concentration ◽  
Planar Laser Induced Fluorescence ◽  
Planar Laser

AbstractThe spatially resolved concentration of OH radicals in the effluent of a microwave (MW) surfatron plasma jet was measured by planar laser-induced fluorescence. Two cases were compared – constant MW power and MW power modulated by 80 Hz. In both cases the maximal concentration was at the tip of the visible discharge, but for constant MW power the OH was spread over a larger volume. The maximum concentration in both cases was on the order of 10

Relative Effects of Velocity- and Mixture-Coupling in a Thermoacoustically Unstable, Partially-Premixed Flame

2021 ◽  
Author(s):  
Ashwini Karmarkar ◽  
Isaac Boxx ◽  
Jacqueline O'Connor
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Oscillation Mode ◽  
Laser Induced Fluorescence ◽  
Stereoscopic Particle Image Velocimetry ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Planar Laser Induced Fluorescence ◽  
Planar Laser ◽  
The Impact

Abstract Combustion instability, which is the result of a coupling between combustor acoustic modes and unsteady flame heat release rate, is a severely limiting factor in the operability and performance of modern gas turbine engines. This coupling can occur through different coupling pathways, such as flow field fluctuations or equivalence ratio fluctuations. In realistic combustor systems, there are complex hydrodynamic and thermo-chemical processes involved, which can lead to multiple coupling pathways. In this study, we use a model gas turbine combustor with two concentric swirling nozzles of air, separated by a ring of fuel injectors, operating at an elevated pressure of 5 bar. The flow split between the two streams is systematically varied to observe the impact on the flow and flame dynamics. High-speed stereoscopic particle image velocimetry, OH planar laser-induced fluorescence, and acetone planar laser-induced fluorescence are used to obtain information about the velocity field, flame, and fuel-flow behavior, respectively. Depending on the flow conditions, a thermoacoustic oscillation mode or a hydrodynamic mode, identified as the precessing vortex core, is present. Our results show that, for this combustor system, changing the flow split between the two concentric nozzles can alter the dominant harmonic oscillation modes in the system, which can significantly impact the dispersion of fuel into air, thereby modulating the local equivalence ratio of the flame. This insight can be used to design instability control mechanisms in real gas turbine engines.

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