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The effect of support fibers on micro-convection in droplet combustion experiments

Published on Jan 1, 2015
· DOI :10.1016/j.proci.2014.07.022
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University),
Yuhao Xu7
Estimated H-index: 7
(Cornell University)
+ 1 AuthorsMichael C. Hicks8
Estimated H-index: 8
(Glenn Research Center)
Cite
Abstract
Abstract This study reports experimental evidence of gas phase micro-convection induced by support fibers used in droplet combustion experimentation. Soot aggregates formed during combustion of n-octane and n-decane droplets (initial diameters ranging from 0.5 mm to 5 mm) provide natural seeds to reveal the thermal and flow asymmetries involved. The experiments are carried out in an environment that reduces the influence of forced and buoyant convection for both free-floating (unsupported) and fiber-supported droplets. Under these conditions, the soot trapping patterns (due to a balance of thermophoretic and flow-induced drag) would be spherical. However, this situation is only observed for unsupported droplets, or for fiber-supported droplets when the fiber is small relative to the droplet diameter. For D o o > 1 mm the International Space Station provided capabilities for anchoring test droplets onto a single 80 μm SiC fiber, and for deploying unsupported droplets. Results clearly indicate that a non-symmetric gas flow field exists in some cases (i.e., for 1 mm o
  • References (23)
  • Citations (11)
Cite
References23
Newest
Published on Mar 1, 2013in Combustion and Flame4.12
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University),
Tanvir Farouk17
Estimated H-index: 17
(USC: University of South Carolina)
+ 2 AuthorsC. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
This study presents an experimental effort and detailed numerical simulation of the burning process of an ester-based biodiesel fuel droplet – methyl decanoate (MD). The experiments are carried out using test droplets that are anchored to small SiC support structures (14 lm diameter) and that burn in an ambience subjected to a low gravity level to promote spherical symmetry in the droplet burning process. The initial droplet diameters are 0.53–0.57 mm and the combustion gas is normal atmospheric...
Published on Jan 1, 2013
Hiroshi Nomura9
Estimated H-index: 9
(College of Industrial Technology),
Hiromu Takahashi1
Estimated H-index: 1
(College of Industrial Technology)
+ 1 AuthorsMasao Kikuchi7
Estimated H-index: 7
(JAXA: Japan Aerospace Exploration Agency)
Abstract Combustion experiments of fuel droplet array in fuel-vapor/air mixture were performed at normal and microgravities to investigate mechanism of flame spread. A 10-droplet array was inserted into the test section filled with a saturated fuel-vapor/air mixture as a simple model of prevaporized sprays. Gas equivalence ratio of the fuel-vapor/air mixture was controlled by the test section temperature. n -Decane droplets of 0.8 mm in the initial diameter were employed. The first droplet was i...
Published on Jan 1, 2013
Shinji Nakaya8
Estimated H-index: 8
(UTokyo: University of Tokyo),
Kotaro Fujishima1
Estimated H-index: 1
(UTokyo: University of Tokyo)
+ 2 AuthorsDaisuke Segawa10
Estimated H-index: 10
(OPU: Osaka Prefecture University)
Abstract The burning characteristics of isolated fuel droplets for ethanol, 1-butanol and n -decane were experimentally examined in carbon dioxide-rich or argon-rich environments under microgravity. The ambience consisted of oxygen, nitrogen, carbon dioxide and argon. The concentration of oxygen was fixed to be 21% in volume percentage, and that of carbon dioxide or argon was varied from 0% to 60% in volume percentage. Detailed measurements of the droplet surface areas were conducted using a hig...
Published on Jan 1, 2013
Tanvir Farouk17
Estimated H-index: 17
(Princeton University),
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University)
+ 2 AuthorsFrederick L. Dryer66
Estimated H-index: 66
(Princeton University)
Abstract Combustion characteristics of isolated sub-millimeter sized methyl butanoate (MB) droplets are studied at low gravity (10 −4 m/s 2 ) in a 1.2 s drop tower. In the experiments, droplets were grown and deployed onto the intersection of two 14 μm silicon carbide fibers in a cross-string arrangement and exposed to symmetrically placed spark ignition sources. The initial droplet diameter was fixed at 0.54 ± 0.01 mm, and experiments were carried out in room temperature air at atmospheric pres...
Published on Sep 5, 2012in Image Analysis & Stereology1.78
Christopher Dembia6
Estimated H-index: 6
(Cornell University),
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University),
C. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
A simple automated image analysis algorithm has been developed that processes consecutive images from high speed, high resolution digital images of burning fuel droplets. The droplets burn under conditions that promote spherical symmetry. The algorithm performs the tasks of edge detection of the droplet’s boundary using a grayscale intensity threshold, and shape fitting either a circle or ellipse to the droplet’s boundary. The results are compared to manual measurements of droplet diameters done...
Published on Feb 1, 2012in Combustion and Flame4.12
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University),
C. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
Abstract The droplet burning characteristics of binary blends of iso-octane, n -heptane and toluene were studied in an ambience that minimizes external convection and promotes spherical droplet flames. The results are compared to gasoline (87 octane rating). The initial droplet diameter was fixed at 0.51 ± 0.02 mm and the experiments were carried out in room temperature air. Measurements of the evolution of droplet diameter show that iso-octane, n -heptane and their mixtures have almost identica...
Published on Jan 1, 2012in Combustion and Flame4.12
Tanvir Farouk17
Estimated H-index: 17
(Princeton University),
Frederick L. Dryer66
Estimated H-index: 66
(Princeton University)
Abstract Tethered methanol droplet combustion in carbon dioxide enriched environment is simulated using a transient one-dimensional spherosymmetric droplet combustion model that includes the effects of tethering. A priori numerical predictions are compared against recent experimental data. The numerical predictions compare favorably with the experimental results and show significant effects of tethering on the experimental observations. The presence of a relatively large quartz fiber tether incr...
Published on Aug 1, 2010in Combustion and Flame4.12
Michael C. Hicks8
Estimated H-index: 8
(Glenn Research Center),
Vedha Nayagam13
Estimated H-index: 13
(Glenn Research Center),
Forman A. Williams48
Estimated H-index: 48
(UCSD: University of California, San Diego)
Diffusive extinction of methanol droplets with initial diameters between 1.25 mm and 1.72 mm, burning in a quiescent microgravity environment at one atmosphere pressure, was obtained experimentally for varying levels of ambient carbon-dioxide concentrations with a fixed oxygen concentration of 21% and a balance of nitrogen. These experiments serve as precursors to those which are beginning to be performed on the International Space Station and are motivated by the need to understand the effectiv...
Published on Nov 1, 2005in Combustion and Flame4.12
Alberto Cuoci27
Estimated H-index: 27
(Polytechnic University of Milan),
Marco Mehl27
Estimated H-index: 27
(Polytechnic University of Milan)
+ 3 AuthorsE. Ranzi7
Estimated H-index: 7
(Polytechnic University of Milan)
This paper presents a mathematical model for the unsteady evaporation, ignition, and combustion of isolated fuel droplets under microgravity. The model consists of a large structured system of differential algebraic equations, where the numerical complexity is due both to the stiff nature of the kinetic mechanism and to the flame structure around the droplet. A very general, detailed kinetic scheme, consisting of ∼200 species and over 5000 reactions, is used to describe the gas-phase combustion ...
Cited By11
Newest
Abstract The influence of the suspender on the evaporation of droplets under quiescent atmospheric conditions was studied experimentally using pendant droplets of ethanol (volatile) and water (non-volatile). Conducting and non-conducting suspenders of different materials and configurations (a steel needle, glass needle, steel rod, and glass rod) were evaluated. For both liquids, it is observed that the rate of evaporation is higher with steel suspenders. More importantly, for ethanol droplets, t...
Published on May 1, 2019in Combustion and Flame4.12
Álvaro Muelas (University of Zaragoza), Pilar Remacha1
Estimated H-index: 1
(University of Zaragoza),
Javier Ballester22
Estimated H-index: 22
(University of Zaragoza)
Abstract The droplet combustion characteristics of conventional heating oil, UCO biodiesel and their mixtures (10 and 20% biodiesel by volume) were examined in a free-falling droplet combustion facility designed to approach the typical temperature and oxygen conditions around individual droplets in real boiler flames. Moreover, and given the importance of avoiding effects due to gravity or convection in this type of experiments, the quite spherical soot shells recorded (infrequent event in free-...
Published on Jan 1, 2019in International Journal of Heat and Mass Transfer4.35
Christian Chauveau21
Estimated H-index: 21
(CNRS: Centre national de la recherche scientifique),
Madjid Birouk16
Estimated H-index: 16
(UM: University of Manitoba)
+ 1 AuthorsIskender Gökalp30
Estimated H-index: 30
(CNRS: Centre national de la recherche scientifique)
Abstract This paper presents an analysis of the effect of the droplet support fiber on the droplet evaporation process. This effect is evaluated for a droplet evaporating in a hot environment at atmospheric pressure using the experimental results of the present study and those in the literature. Selected published results are acquired using similar test conditions and experimental setups as the present data. The only main difference between these studies is the droplet support fiber diameter whi...
Published on Aug 1, 2018in Microgravity Science and Technology1.97
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Yasuko Yoshida1
Estimated H-index: 1
(Yamaguchi University)
+ 4 AuthorsMasaki Nokura1
Estimated H-index: 1
This research conducted microgravity experiments on the flame spread over randomly distributed n-decane-droplet clouds aboard the Japanese Experiment Module “Kibo” on the International Space Station. 67-152 droplets were distributed at intersections of a 30 × 30 square lattice with 14-micron SiC fibers placed in a combustion chamber. One droplet on the bottom side of lattice was ignited by a hot-wire igniter to start the flame spread. The burning behavior was observed by a digital camera. This p...
Published on Jul 1, 2018in Combustion and Flame4.12
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Naoya Motomatsu1
Estimated H-index: 1
(Yamaguchi University)
+ 2 AuthorsTakehiko Seo4
Estimated H-index: 4
(Yamaguchi University)
Abstract This research investigates the flame-spread characteristics between two droplets, Droplets A and L, of different diameter. n -Decane droplets are placed at intersections of 14 µ SiC fibers. The flame spread from Droplet A to Droplet L was observed in microgravity. The results show that the flame-spread rate decreases with an increase in the droplet spacing or the initial diameter of Droplet L for a constant initial diameter of Droplet A. The flame-spread time is approximated as the summ...
Published on Jan 1, 2017
Yuhao Xu7
Estimated H-index: 7
(Cornell University),
Michael C. Hicks8
Estimated H-index: 8
(Glenn Research Center),
C. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
Abstract The burning characteristics of iso -octane droplets in the standard atmosphere are reported over a large range of initial droplet diameters (0.5 mm D o 5 mm) for near one-dimensional droplet flames as promoted by low gravity. A ground-based drop tower and a space-based platform (International Space Station) were used to provide an environment to examine the influence of D o that encompasses regimes where radiation does not have an effect on burning to where it does. For D o K ) was near...
Published on Sep 1, 2016in Combustion and Flame4.12
Yu Cheng Liu10
Estimated H-index: 10
(UM: University of Michigan),
Yuhao Xu7
Estimated H-index: 7
(Cornell University)
+ 1 AuthorsC. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
Abstract This paper reports the results of a comprehensive experimental study on the effect of initial droplet diameter ( D o ) over a very wide range (0.5 mm D o n -heptane, n -octane and n -decane – that are representative of components found in petroleum-based transportation fuels and their surrogates. Spherical symmetry in the burning process was promoted by carrying out the experiments in a reduced convection (stagnant ambience) and buoyancy (low gravity) environment using the facilities of...
Published on Jul 1, 2016in Combustion and Flame4.12
Yu Cheng Liu10
Estimated H-index: 10
(UM: University of Michigan),
Fahd E. Alam4
Estimated H-index: 4
(USC: University of South Carolina)
+ 3 AuthorsTanvir I. Farouk4
Estimated H-index: 4
(USC: University of South Carolina)
Abstract This study reports results of experiments on the isolated droplet burning characteristics of butanol isomers ( n -, iso -, sec -, and tert -) under standard atmosphere conditions in an environment that promotes spherical combustion. The data are compared with predictions from a detailed numerical model (DNM) that incorporates complex combustion chemistry, radiative heat transfer, temperature dependent variable fluid properties, and unsteady gas and liquid transport. Computational predic...
Published on Mar 1, 2016in Fuel5.13
Yuhao Xu7
Estimated H-index: 7
(Cornell University),
Ivan Keresztes18
Estimated H-index: 18
(Cornell University)
+ 3 AuthorsC. Thomas Avedisian14
Estimated H-index: 14
(Cornell University)
Abstract Fuels derived from bio-feedstocks have received significant attention for their potential to reduce the consumption of petroleum-based liquid fuels, either through blending or direct use. Biofuels produced from heterotrophic microalgae are particularly attractive because of fast conversion of sustainable plant sugars into renewable oils of controllable quality and composition, but without the need for sunlight or carbon from the atmosphere for growth. This paper describes the results of...
Published on May 21, 2015in Energy & Fuels3.02
Yuhao Xu7
Estimated H-index: 7
,
C. Thomas Avedisian14
Estimated H-index: 14
Fuels derived from biofeedstocks are receiving attention for their potential as additives to conventional petroleum-based transportation fuels. Normal butanol, in particular, can enhance performance compared to ethanol because of its higher energy density. To better understand the combustion dynamics of n-butanol in the context of gasoline, experiments are reported here to examine the isolated droplet combustion characteristics of an 87 octane (ethanol-free) gasoline and a mixture of gasoline (0...
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