Effects of Gravity on Soot Formation in a Coflow Laminar Methane/Air Diffusion Flame

Wenjun, None KONG; Liu, Fengshan

doi:10.1007/s12217-009-9175-z

Cited by 15 publications

(5 citation statements)

References 32 publications

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“…Kong and Liu [7] recently simulated laminar coflow methane/air diffusion flames and studied the effects of the air coflow velocity. The peak soot volume fraction in microgravity was found to be about twice that in normal gravity [8]. Liu et al [9] computed the influence of heat transfer and radiation on the structure and soot formation characteristics of a coflow laminar ethylene/air diffusion flame and showed that radiative heat loss plays a major role in the flame structure in microgravity.…”

Section: Introductionmentioning

confidence: 99%

An experimental and computational study of soot formation in a coflow jet flame under microgravity and normal gravity

Cao

Giassi

et al. 2015

Proceedings of the Combustion Institute

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Upon the completion of the Structure and Liftoff in Combustion Experiment (SLICE) in March 2012, a comprehensive and unique set of microgravity coflow diffusion flame data was obtained. This data covers a range of conditions from weak flames near extinction to strong, highly sooting flames, and enabled the study of gravitational effects on phenomena such as liftoff, blowout and soot formation. The microgravity experiment was carried out in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS), while the normal gravity experiment was performed at Yale utilizing a copy of the flight hardware. Computational simulations of microgravity and normal gravity flames were also carried out to facilitate understanding of the experimental observations. This paper focuses on the different sooting behaviors of CH 4 coflow jet flames in microgravity and normal gravity. The unique set of data serves as an excellent test case for developing more accurate computational models. Experimentally, the flame shape and size, lift-off height, and soot temperature were determined from line-of-sight flame emission images taken with a color digital camera. Soot volume fraction was determined by performing an absolute light calibration using the incandescence from a flame-heated thermocouple. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the chemically reacting flow, and the soot evolution was modeled by the sectional aerosol equations. The governing equations and boundary conditions were discretized on an axisymmetric computational domain by finite differences, and the resulting system of fully coupled, highly nonlinear equations was solved by a damped, modified Newton's method. The microgravity sooting flames were found to have lower soot temperatures and higher volume fraction than their normal gravity counterparts. The soot distribution tends to shift from the centerline of the flame to the wings from normal gravity to microgravity.

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Section: Introductionmentioning

confidence: 99%

An experimental and computational study of soot formation in a coflow jet flame under microgravity and normal gravity

Cao

Giassi

et al. 2015

Proceedings of the Combustion Institute

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“…Recently, Guibaud et al [11] developed embedded optical techniques to explore the radiant heat feedback related to soot in flame propagation in microgravity. Kong and Liu [12][13] numerically studied the effect of gravity on soot formation characteristics by simulating a laminar methane/air diffusion flame. The results showed that changing gravity alters the location and intensity of soot nucleation and surface growth.…”

Section: Soot Formationmentioning

confidence: 99%

A review of motivations, methods, and achievements on microgravity combustion research

Hao²,

Guo³

et al. 2021

E3S Web Conf.

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Microgravity combustion has always been one of the key and frontier research fields in the international combustion community. Why has microgravity combustion attracted so much attention? First of all, fire safety and combustion reliability are imminent to spacecraft. Secondly, the convection effect is weakened in the microgravity environment, and the basic combustion phenomena are more prominent, which is greatly helpful to study the fundamental laws of combustion and develop reliable combustion models for fuels. This article systematically summarized and analyzed the research focuses, namely fire safety of spacecraft, droplet combustion, soot formation and flame structures, and current research status in the field of microgravity combustion during the past decades of years. In this paper, motivations, methods, and achievements of fire safety in spacecraft and fundamental combustion characteristics in microgravity were analyzed, which provide a comprehensive review for the microgravity combustion research. Suggestions for the development direction of microgravity combustion science were also made. Improving the application of efficient and clean combustion and optimizing fire safety strategies of new generation spacecraft materials should still be regarded as two critical targets in the future.

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“…More importantly, their simulation did not reach steady-state conditions within 3s of imposing microgravity which is the time period in drop tower experiments. Kong and Liu [13,14], Liu et al [15], and Charest et al [16,17] also numerically investigated the influence of gravity on laminar coflow diffusion flames, demonstrating that the µg flame has lower temperatures, thicker soot regions and higher soot volume fractions than the 1g flame.…”

Section: Introductionmentioning

confidence: 99%

A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity

Veshkini¹,

Dworkin²

2023

Preprint

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A numerical study is conducted of methane-air coflow diffusion flames at microgravity (μg) and normal gravity (lg), and comparisons are made with experimental data in the literature. The model employed uses a detailed gas phase chemical kinetic mechanism that includes PAH formation and growth, and is coupled to a sectional soot particle dynamics model. The model is able to accurately predict the trends observed experimentally with reduction of gravity without any tuning of the model for different flames. The microgravity sooting flames were found to have lower temperatures and higher volume fraction than their normal gravity counterparts. In the absence of gravity, the flame radii increase due to elimination of buoyance forces and reduction of flow velocity, which is consistent with experimental observations. Soot formation along the wings is seen to be surface growth dominated, while PAH condensation plays a more major role on centerline soot formation. Surface growth and PAH growth increase in microgravity primarily due to increases in the residence time inside the flame. The rate of increase of surface growth is more significant compared to PAH growth, which causes soot distribution to shift from the centerline of the flame to the wings in microgravity. Keywords: laminar diffusion flame,methane-air,microgravity, soot formation, numerical modelling

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Effects of Gravity on Soot Formation in a Coflow Laminar Methane/Air Diffusion Flame

Cited by 15 publications

References 32 publications

An experimental and computational study of soot formation in a coflow jet flame under microgravity and normal gravity

An experimental and computational study of soot formation in a coflow jet flame under microgravity and normal gravity

A review of motivations, methods, and achievements on microgravity combustion research

A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity

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