High-pressure combustion of submillimeter-sized nonane droplets in a low convection environment

Published on May 1, 2006in Combustion and Flame4.12
· DOI :10.1016/j.combustflame.2005.12.008
J.H. Bae2
Estimated H-index: 2
(Cornell University),
C.T. Avedisian24
Estimated H-index: 24
(Cornell University)
Abstract An experimental study of droplet combustion of nonane (C 9 H 20 ) at elevated pressures burning in air is reported using low gravity and small droplets to promote spherical gas-phase symmetry at pressures up to 30 atm (absolute). The initial droplet diameters range from 0.57 to 0.63 mm and they were ignited by two electrically heated hot wires positioned horizontally on opposite sides of the droplet. The droplet and flame characteristics were recorded by a 16-mm high-speed movie and a high-resolution video camera, respectively. A photodiode is used to measure broadband gray-body emission from the droplet flames and to track its dependence on pressure. Increasing the pressure significantly influences the ability to make quantitative measurements of droplet, soot cloud, and luminous zone diameters. At pressures as low as 2 atm, soot aggregates surrounding the droplet show significant coagulation and agglomeration and at higher pressures the soot cloud completely obscures the droplet, with the result being that the droplet could not be measured. Above 10 atm radiant emissions from hot soot particles are extensive and the resulting flame luminosity further obscures the droplet. Photographs of the luminous zone in subcritical pressures show qualitatively that increasing pressure produces more soot, and the mean photodiode voltage output increases monotonically with pressure. The maximum flame and soot shell diameters shift to later times as pressure increases and the soot shell is located closer to the flame at higher pressure. The soot shell and flame diameter data are correlated by a functional relationship of reduced pressure derived from scaling the drag and thermophoretic forces on aggregates that consolidates all of the data onto a single curve.
  • References (34)
  • Citations (12)
📖 Papers frequently viewed together
6 Citations
30 Citations
62 Citations
78% of Scinapse members use related papers. After signing in, all features are FREE.
#1Lorenz RatkeH-Index: 25
#2Hannes U. WalterH-Index: 1
Last. Berndt FeuerbacherH-Index: 2
view all 3 authors...
55 Citations
The combustion of JP8 (a kerosene-based fuel) mixed with up to 20% (volume) tripropylene glycol monomethyl ether (TPGME, CH3[CH2CH(CH3)O]3OH) is studied to examine the influence of composition on soot dynamics for the configuration of an isolated and stationary droplet burning with nearly spherical symmetry. The spherical droplet flame is characterized by a one-dimensional transport process with a concentric flame and droplet, and a sooting configuration for which the soot aggregates are trapped...
3 CitationsSource
#1J.H. Bae (Cornell University)H-Index: 2
#2C.T. Avedisian (Cornell University)H-Index: 24
Combustion of stationary JP8 fuel droplets mixed with additives is examined in a low gravity environment to reduce the influence of convection and promote spherical droplet flames. Both qualitative information on flame structure and sooting tendencies and quantitative information on evaporation rates and flame and soot shell diameters are reported. The additives were hexanol (C6H14O) and a commercial blend of a detergent/dispersant termed “+100” that is widely used as an additive in military tra...
24 CitationsSource
#1Gabi Ben-Dor (BGU: Ben-Gurion University of the Negev)H-Index: 32
#2Tov Elperin (BGU: Ben-Gurion University of the Negev)H-Index: 29
Last. B. Krasovit (BGU: Ben-Gurion University of the Negev)H-Index: 1
view all 3 authors...
Numerical analysis of the effect of thermo- and diffusiophoretic forces on the motion of moderately large (0.01 ≤ Kn ≤ 0.3) combustion-generated (soot) particles and on the formation of soot-shell structure in the buoyancy-free spherical droplet flames is performed. Transient evaporation, ignition and combustion of a single sooting-fuel droplet immersed into a quiescent hot environment are considered, taking into account the effects of radiative heat losses, variable transport properties and the...
15 CitationsSource
The critical temperature for soot formation in diffusion flames has been the subject of prior measurements by various investigators. More recently, the presence of soot precursor particles in a variety of diffusion flames has been recognized, and the Arrhenius reaction rate constants for their conversion to carbonaceous soot have been reported. In this work the prediction of the soot inception temperature using the recent carbonization reaction rate data is investigated when temperature increase...
81 CitationsSource
#1Hideaki Kobayashi (Tohoku University)H-Index: 34
#2Jeong ParkH-Index: 2
Last. Takashi Niioka (Tohoku University)H-Index: 22
view all 4 authors...
The flame spread phenomena of an n -decane droplet array in the supercritical pressure range were experimentally investigated in microgravity. Experiments were conducted at presure up to 5.0 MPa, which is over the critical pressure of n -decane. Observations of the flame-spread phenomenon were conducted using OH-radical emission, Schlieren, and back-klit images recorded by a high-speed video camera. The flame-spread rates were calculated on the basis of the time history of the OH-emission images...
21 CitationsSource
Thetrappingandtransportofsootaggregatesbetweenaburningsuspendeddropletanditse ameinaconvectionfree (microgravity ) environment are discussed. Many researchers have utilized the suspended droplet method for studying droplet combustion in microgravity where the intentis to createa spherically symmetric burning process. In the ideal case, soot particles are trapped in a spherical shell-like structure between the droplet and the e ame. Resultspresented showthatthee bersupport canpreventtheformation ...
30 CitationsSource
#1Keiichi Okai (UTokyo: University of Tokyo)H-Index: 4
#2Yutaka Ono (UTokyo: University of Tokyo)H-Index: 1
Last. F.A. Williams (UCSD: University of California, San Diego)H-Index: 2
view all 9 authors...
The interactive combustion of two closely-spaced droplets at elevated pressures was investigated experimentally in a 2.2 second drop tower. Heptane, hexadecane and mixtures of the two were the fuel. A nitrogen-Oxygen ambient with a relatively low oxygen concentration faciliated observation of droplets during combustion at elevated pressures. Results show that staged combustion of binary fuel droplets still exists for interacting droplets at elevated pressures. For pure fuels, the interaction eff...
1 CitationsSource
#1Josette Bellan (California Institute of Technology)H-Index: 33
A critical review of recent investigations in the realm of supercritical (and subcritical) fluid behavior is presented with the goal of obtaining a perspective on the peculiarities of high pressure observations. Experiments with drops, isolated or in groups, streams, shear and mixing layers, jets and sprays are tabulated and discussed as a precursor to forming a conceptual picture of fluid comportment. The physics of fluid behavior in the supercritical and subcritical regimes is discussed, and m...
188 CitationsSource
#1C. Thomas Avedisian (Cornell University)H-Index: 15
#2Brian J. Callahan (Cornell University)H-Index: 1
30 CitationsSource
Cited By12
Last. Yang Zhang (University of Sheffield)H-Index: 18
view all 2 authors...
Abstract The liquid-phase processes occurring during fuel droplet combustion are important in deciding the behaviour of the overall combustion process, especially, for the binary fuel droplets. Hence, understanding these processes is essential for explaining the combustion of the binary fuel droplet. However, experimental investigation of such processes is not easily accomplishable due to the very short period of time available for tracking them within the finely small fuel droplet. In the prese...
#1Hiroshi Nomura (College of Industrial Technology)H-Index: 10
#2Shinji Nakaya (UTokyo: University of Tokyo)H-Index: 9
Last. Mitsuhiro Tsue (UTokyo: University of Tokyo)H-Index: 17
view all 3 authors...
#1Daniel L. Dietrich (Glenn Research Center)H-Index: 14
#2R. CalabriaH-Index: 1
Last. Forman A. Williams (UCSD: University of California, San Diego)H-Index: 58
view all 5 authors...
ABSTRACTThis article presents the results of experiments conducted aboard the International Space Station involving the combustion of large bi-component droplets of decane and hexanol (50/50 by volume) in air ambients with ambient pressures between 0.05 and 0.30 MPa. The experiments showed the presence of sustained low-temperature or cool-flame burning following radiative extinction of large droplets at ambient pressures greater than or equal to 0.10 MPa. The droplet diameters at cool-flame exti...
8 CitationsSource
#1Hua Meng (ZJU: Zhejiang University)H-Index: 26
#2Vigor Yang (Georgia Institute of Technology)H-Index: 57
Abstract Vaporization of two liquid oxygen (LOX) droplets in tandem in supercritical convective hydrogen environments has been numerically investigated. The theoretical formulation consists of a complete set of conservation equations of mass, momentum, energy, and species concentrations. The solution technique is based on a unified treatment of general fluid thermodynamics incorporated into a dual time-stepping preconditioning approach. In addition, a self-consistent property evaluation method i...
9 CitationsSource
#1Yu Cheng Liu (Cornell University)H-Index: 11
#2Tanvir Farouk (USC: University of South Carolina)H-Index: 19
Last. C. Thomas Avedisian (Cornell University)H-Index: 15
view all 5 authors...
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...
18 CitationsSource
#1Chun Kuei Chen (NCKU: National Cheng Kung University)H-Index: 2
#2Ta Hui Lin (NCKU: National Cheng Kung University)H-Index: 19
Abstract The spatial distribution of drops and their interactions are influential parameters in spray combustion. Most available researches on this subject were about lateral spacing or were performed in micro-gravity. Studies about upstream/downstream convective interaction of burning drops are scarce. In this study, drop strings of different spacing were investigated in a high-temperature oxidizing environment for their flame transition, flame width variation and drop evaporation rate. The fla...
6 CitationsSource
#1Yu Cheng Liu (Cornell University)H-Index: 11
#2C. Thomas Avedisian (Cornell University)H-Index: 15
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...
29 CitationsSource
#1Mariko Nakamura (Osaka University)H-Index: 3
#2Daichi Nishioka (Osaka University)H-Index: 1
Last. Fumiteru Akamatsu (Osaka University)H-Index: 16
view all 4 authors...
Abstract Coaxial jet spray flames of kerosene and oxygen are experimentally studied over a pressure range of 0.1–1.0 MPa to determine the relationship between flame structure, droplet behavior, and soot formation region, which varies with changes in pressure. The direct images and chemiluminescence spectra show that the spray flames have three regions: the blue flame region, which has a peak of CH* and C 2 * radical chemiluminescence, luminous flame region caused by soot emission, and blue emiss...
14 CitationsSource
#1Shinji Nakaya (OPU: Osaka Prefecture University)H-Index: 6
#2Daisuke Segawa (OPU: Osaka Prefecture University)H-Index: 10
Last. Tomoya Furuta (OPU: Osaka Prefecture University)H-Index: 1
view all 5 authors...
Abstract The burning and sooting behaviors of isolated fuel droplets for ethanol and n -decane are examined in high concentration of the ambient carbon dioxide under microgravity. A quartz fiber with the diameter of 50 μm maintains the droplet in the center of the combustion chamber and the range in the initial droplet diameter is from 0.30 to 0.80 mm. The ambience consists of oxygen, nitrogen and carbon dioxide. The concentration of oxygen is 21% in volume, and that of carbon dioxide is varied ...
6 CitationsSource