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Proceedings ArticleDOI

Soot Suppression in Laminar Jet Diffusion Flames by Shear

08 Jan 2018-

About: The article was published on 2018-01-08. It has received 1 citation(s) till now. The article focuses on the topic(s): Laminar flow.
Topics: Laminar flow (56%)
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Proceedings ArticleDOI
01 Jun 2018-
Abstract: Combustion in itself is a complex phenomenon that involves the interaction and interplay of multiple phenomena, the combined effect of which give rise to the common flame that we see and use in our daily life applications from cooking to propelling our vehicles to space. The least thing that goes unnoticed about these flames is the effect of the various phenomena from its surrounding environment that affects its behaviour and properties. These phenomena cause a variety of energy interactions that lead to various types of energy transformations which in turn affect the flame behaviour. This paper focuses on experimentally investigating the effect of one such phenomenon, which is the acoustics or sound energy on partially premixed flames. The subject in itself is extensively studied upon as thermo-acoustics globally, whereas the current work focuses on studying its effect on soot formation of partially premixed flames. The said effect is studied in this research work by the use of a butane as fuel, fitted with a nozzle that houses 3 arrays consisting of 4 holes each that are placed equidistant to each other for entraining air and the resulting flame is impinged with sound from two independent and similar sound sources that are placed equidistant from the centre of the nozzle. The entire process is systematically video graphed using a 60 fps regular CCD and analysed for variation in flame heights and flickering frequencies where the fuel mass flow rate is maintained constant and the configuration of entrainment holes and frequency of sound are varied, whilst maintaining constant ambient atmospheric conditions. The current work establishes significant outcomes on the effect of acoustics on soot formation; it is noteworthy that soot formation is the main cause of pollution and a major cause of inefficiency of current propulsion systems. This work is one of its kinds and its outcomes are widely applicable to commercial and domestic appliances that utilise combustion for energy generation or propulsion and help us understand them better, so that we can increase their efficiency and

Cites background from "Soot Suppression in Laminar Jet Dif..."

  • ...Soot suppression increased along with higher external shear for all the fuel flow rates [12]....


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01 Jan 2006-

524 citations

Journal ArticleDOI
D. X. Du1, Richard L. Axelbaum1, Chung K. Law1Institutions (1)
01 Jan 1991-
Abstract: A study of carbon dioxide and oxygen addition on soot formation has been performed such that the effects of dilution, temperature and direct chemical participation have been isolated for the additives on both the fuel and oxidizer sides. By measuring soot inception limits in the counterflow flame and integrated soot volume fractions in the coflow flame, the influence of the additives on soot inception, growth and burnout has also been ascertained. Results demonstrate that carbon dioxide, whether added to the fuel or oxidizer side, can suppress soot formation chemically. The effect of oxygen addition is more complex. When added to the fuel side of an ethylene flame, the addition leads to an abrupt increase in the inception limit, indicating that the inception chemistry has been accelerated. The addition to propane, however, is initially suppressive and results in a significant reduction in the soot inception limit which is more than can be accounted for by dilution. The addition becomes promoting as the oxygen mole fraction approaches 40%. Finally, the effect of oxygen concentration on the oxidizer side, for both ethylene and propane flames, is almost totally thermal.

155 citations

Journal ArticleDOI
D.H. Cotton1, N.J. Friswell1, D.R. Jenkins1Institutions (1)
Abstract: A propane diffusion flame has been used to examine the mechanism of soot removal by metallic additives. Forty metals have been studied, and their efficiencies of soot removal in this flame are given. A semiquantitative mechanism is proposed for the alkaline earth metals; its basis is that these metals undergo a homogeneous, gas-phase reaction with flame gases to produce hydroxyl radicals which rapidly remove soot or soot precursors. The mechanism is supported by measurements of free-radical recombination catalysis by the alkaline earths in premixed hydrogen-oxygen-nitrogen flames. Soot removal by most other metals studied is thought to occur by different mechanisms, and possible ones are discussed qualitatively.

105 citations

Journal ArticleDOI
Kwang Chul Oh, Hyun Dong Shin1Institutions (1)
01 Mar 2006-Fuel
Abstract: The influence of oxygen concentration and carbon dioxide as diluents in the oxidizer side on soot formation was studied by Time Resolved Laser Induced Incandescence (TIRE-LII) and TEM photography in non-premixed co-flowing flames. TIRE-LII method was used to measure the distribution of two-dimensional soot volume fraction and primary particle size. The soot was directly sampled by the thermophoretic method, and its diameter was examined by TEM photography. Two suitable delay times of the TIRE-LII method affecting measurable range and sensitivity were determined by comparing TEM photographs with the TIRE-LII signal. The effects of oxygen concentration and carbon dioxide as diluents in the oxidizer side on soot formation were investigated with these calibrated techniques. An O 2 +(CO 2 , N 2 , and [Ar+CO 2 ]) mixtures in co-flow were used to isolate carbon dioxide effects systematically. The primary particle number concentration and soot volume fraction were abruptly decreased by the addition of carbon dioxide to co-flow. This suppression was resulted from the short residence time in inception region because of the late nucleation and the decrease of surface growth distance by the low flame temperature due to the higher thermal capacity and the chemical change of carbon dioxide. The increase of oxygen concentration in the co-flow caused an enhancement of soot nucleation and thus the residence time increase, but the specific growth rate showed almost the same value regardless of the co-flow mixture in the growth region. This result suggests that the specific growth rate has a weak dependence on the relative change of co-flow conditions in non-premixed co-flowing flames.

96 citations

Journal ArticleDOI
Min Suk Cha1, S. M. Lee1, K.T. Kim1, Suk Ho Chung2Institutions (2)
Abstract: The effect of nonthermal plasma on diffusion flames in coflow jets has been studied experimentally by adopting a dielectric barrier discharge (DBD) technique. The plasma reactor had wire-cylinder-type electrodes with AC power supply operated at 400 Hz. The effect of flame on the behavior of electrical discharge was first investigated to identify the regime of plasma generation, discharge onset voltage, and delivered power to the plasma reactor. The generation of streamers was enhanced with a flame by the increase in the reduced electric field intensity due to high-temperature burnt gas and by the abundance of ions in the flame region. The effect of streamers on flame behavior reveals that the flame length was significantly decreased as the applied voltage increased. The yellow luminosity by the radiation of soot particles was also significantly diminished. The temperature of burnt gases, the concentrations of major species, and the spatial distribution of OH radical, PAH, and soot have been measured. The formation of PAH and soot was influenced appreciably by the nonthermal plasma, while the flame temperature and the concentration of major species were not influenced much with the plasma generation. The results demonstrated that the application of nonthermal plasmas can effectively suppress PAH and soot formation in the flames with low power consumption even in the order of 1 W.

80 citations

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