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Influence of Gravity and Ambient Pressure on Combustion and Flammability of n-Heptane and 1-Propanol Droplets in Air-Diluent Environments

Published on Oct 1, 2011in Combustion Science and Technology1.56
· DOI :10.1080/00102202.2010.498798
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
J. B. Wei4
Estimated H-index: 4
(UC Davis: University of California, Davis)
Cite
Abstract
Reduced gravity and normal gravity combustion experiments were performed with individual fiber-supported n-heptane and 1-propanol droplets with initial diameters in the 1-mm size range. Experiments were performed with air-inert mixtures at 0.1 MPa or 0.3 MPa and about 298 K, where helium, carbon dioxide, or xenon were separately used as inerts. The amount of inert gas required to suppress combustion was generally higher in reduced gravity than normal gravity, and higher mole fractions of xenon were required for suppression of combustion relative to helium or carbon dioxide. Helium was found to perform the best as a flame suppressant on a mass basis, i.e., mass fractions of helium required to suppress combustion were significantly smaller than for the other inert gases. Increasing the amount of inert gas generally decreased burning rates. Results indicate that ambient gas transport properties and the fuel type play an important role in determining flammability and combustion behaviors of the droplets. Comp...
  • References (27)
  • Citations (7)
Cite
References27
Newest
Published on Jan 1, 1985
F. A. Williams1
Estimated H-index: 1
* Summary of Relevant Aspects of Fluid Dynamics and Chemical Kinetics * Rankine-Hugoniot Relations * Diffusion Flames and Droplet Burning * Reactions in Flows with Negligible Molecular Transport * Theory of Laminar Flames * Detonation Phenomena * Combustion of Solid Propellants * Ignition, Extinction, and Flammability Limits * Combustion Instabilities * Theory of Turbulent Flames * Spray Combustion * Flame Attachment and Flame Spread
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...
Justin Dzik1
Estimated H-index: 1
(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)
The ignition process and burning characteristics of fiber-supported n-heptane fuel droplets in carbon dioxide enriched and varying pressure environments have been studied under normal gravity. Measured values of droplet burning rates, flame dimensions, broad-band radiant emission, and ignition times were compared to droplets burning in standard air conditions. The burning rate constants increased with increasing carbon dioxide concentration or pressure. For 21% ambient oxygen concentration ignit...
Published on Jan 1, 2010in Combustion and Flame4.12
Vedha Nayagam13
Estimated H-index: 13
(Glenn Research Center)
Abstract Recently, Aharon and Shaw developed a simplified analytical expression to predict quasi-steady flame stand-off ratios for alkane fuels. Their analysis is strictly valid only for alkane-type fuels where there is no reabsorption of flame generated species back into the droplet. In this note we show that Aharon and Shaw’s analysis can be extended to methanol droplet combustion where water generated at the flame-sheet is absorbed back into the droplet. The model predictions are shown to com...
Published on Nov 1, 2008in Fire Safety Journal1.66
Shiling Liu1
Estimated H-index: 1
,
Marios C. Soteriou1
Estimated H-index: 1
+ 1 AuthorsJoseph A. Senecal2
Estimated H-index: 2
A model based on the perfectly stirred reactor (PSR) concept is developed and utilized in the prediction of the minimum extinguishing concentration (MEC) of inert fire suppression agents established in the standard cup-burner test. Both physical and chemical mechanisms of fire suppression are considered in PSR modeling. Transport mechanisms are not modeled. Results are contrasted to experimental data and to a semi-analytical approach that assumes heat absorption by the agent is the primary extin...
Published on Oct 1, 2008in Combustion and Flame4.12
Fumiaki Takahashi22
Estimated H-index: 22
(Glenn Research Center),
Gregory T. Linteris25
Estimated H-index: 25
(NIST: National Institute of Standards and Technology),
Viswanath R. Katta25
Estimated H-index: 25
Abstract Microgravity experiments and computations have been conducted to elucidate stabilization and extinguishment mechanisms of methane diffusion flames, in the cup-burner configuration, with CO 2 added gradually to a coflowing air or oxygen-enriched stream. The minimum extinguishing concentration of CO 2 under low oxidizer velocities ( 2 , the Planck mean absorption coefficient was multiplied by a correction factor ( 0 ⩽ C ⩽ 1 ). The fuel-lean peak reactivity spot (the so-called reaction ker...
Published on Feb 18, 2008in Combustion Science and Technology1.56
Seul-Hyun Park7
Estimated H-index: 7
(Drexel University),
Seuk-Cheun Choi1
Estimated H-index: 1
(Drexel University)
+ 1 AuthorsAhmet Yozgatligil8
Estimated H-index: 8
(METU: Middle East Technical University)
Spherically symmetric ethanol droplet combustion experiments were performed to investigate the influence of initial droplet diameter, ambient pressure and inert substitution on the burning and sooting behaviors of ethanol droplet flames. Experiments were performed using the 2.2 sec reduced-gravity droptower facilities at the NASA Glenn Research Center. Noting the importance of transport characteristics of heat and species and their attendant effects on flame temperature and residence time on the...
Published on May 3, 2007in Combustion Science and Technology1.56
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
J. B. Wei4
Estimated H-index: 4
(UC Davis: University of California, Davis)
Abstract Reduced gravity and normal gravity combustion experiments were performed with individual fiber-supported propanol droplets with initial diameters that were typically in the 1.2 to 1.3 mm range. The environment was composed of an air-inert mixture at 0.1 MPa and about 298 K, where helium, carbon dioxide and xenon were separately used as inerts. In the experiments, the amount of inert gas in the environment was progressively increased until droplets could no longer be ignited. Droplet ign...
Published on Jan 1, 2007
J.H. Bae1
Estimated H-index: 1
(Cornell University),
C.T. Avedisian24
Estimated H-index: 24
(Cornell University)
In this paper, we study the influence of inert concentration and initial droplet diameter on nonane (C9H20) droplet combustion in an environment that promotes spherical droplet flames. The oxygen concentration is fixed while the inert is varied between nitrogen and helium. A range of initial droplet diameters (Do) are examined in each ambient gas: 0.4 mm < Do < 0.8 mm; and an oxidizing ambiance consisting of 30% oxygen (fixed) and 70% inert (fixed), with the inert in turn composed of mixtures of...
Published on Jan 1, 2007
Ahmet Yozgatligil8
Estimated H-index: 8
(Drexel University),
Seul-Hyun Park7
Estimated H-index: 7
(Drexel University)
+ 2 AuthorsFrederick L. Dryer66
Estimated H-index: 66
(Princeton University)
Abstract The influence of oxygen (O 2 ) concentration and inert on the sooting and burning behavior of large ethanol droplets under microgravity conditions was investigated through measurements of burning rate, flame temperature, sootshell diameter, and soot volume fraction. The experiments were performed at the NASA Glenn Research Center (GRC) 2.2 s drop tower in Cleveland, OH. Argon (Ar), helium (He), and nitrogen (N 2 ) were used as the inerts and the O 2 concentration was varied between 21% ...
Cited By7
Newest
Published on Mar 21, 2019in Combustion Theory and Modelling1.65
Forman A. Williams48
Estimated H-index: 48
(UCSD: University of California, San Diego),
Vedha Nayagam13
Estimated H-index: 13
(Case Western Reserve University),
Vedha Nayagam4
Estimated H-index: 4
(Case Western Reserve University)
Published on Feb 1, 2016in Combustion Science and Technology1.56
Fahd E. Alam4
Estimated H-index: 4
(USC: University of South Carolina),
Frederick L. Dryer4
Estimated H-index: 4
(Princeton University),
Tanvir I. Farouk4
Estimated H-index: 4
(USC: University of South Carolina)
ABSTRACTThe ‘FLame EXtinguishment’ (FLEX) program conducted by NASA on board the International Space Station (ISS) has been assisting in developing fire-safety protocols for low gravity applications through microgravity droplet combustion experiments. A wide range of fuels, including alcohols and alkanes, have been studied in different ambient conditions that also encompass the use of various diluent species and concentrations. A prime focus of the work has been to observe the relative effective...
Published on Jan 2, 2016in Combustion Science and Technology1.56
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
Chang L. Vang1
Estimated H-index: 1
(UC Davis: University of California, Davis)
ABSTRACTReduced gravity combustion experiments were performed aboard the International Space Station with individual methanol and n-heptane droplets that had initial diameters in the 1.2–5.0-mm-size range. Experiments were performed with air-inert mixtures at 0.1 and 0.07 MPa and about 298 K, where the monatomic gases helium and xenon were separately used as the added inert. These two gases have the same thermodynamic properties on a molar basis, but their transport properties are significantly ...
Published on Oct 1, 2014in Microgravity Science and Technology1.97
Daniel L. Dietrich13
Estimated H-index: 13
(Glenn Research Center),
Vedha Nayagam4
Estimated H-index: 4
(Case Western Reserve University)
+ 9 AuthorsYu Cheng Liu10
Estimated H-index: 10
(Cornell University)
This paper summarizes the first results from isolated droplet combustion experiments performed on the International Space Station (ISS). The long durations of microgravity provided in the ISS enable the measurement of droplet and flame histories over an unprecedented range of conditions. The first experiments were with heptane and methanol as fuels, initial droplet droplet diameters between 1.5 and 5.0 m m, ambient oxygen mole fractions between 0.1 and 0.4, ambient pressures between 0.7 and 3.0 ...
Published on Jun 1, 2014 in WCICA (World Congress on Intelligent Control and Automation)
Huijie Fan (Shenyang Institute of Automation), Yang Cong12
Estimated H-index: 12
(Shenyang Institute of Automation)
+ 2 AuthorsYue Wang (CAS: Chinese Academy of Sciences)
A level set method is proposed for flame front detection and curvature calculation on turbulent premixed OH Planar Laser Induced Fluorescence (OH-PLIF) images. The Flame front on an OH-PLIF image is detected by our proposed curve evolution model. In this model, a global term is designed to make the evolution curve converge to the flame front and a Gaussian kernel function is used to detect the flame front more accurately. For the detected flame front contour, we calculate its curvature using its...
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, 2012in Journal of Combustion
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
Jingbin Wei3
Estimated H-index: 3
Reduced and normal gravity combustion experiments were performed with fiber-supported methanol droplets with initial diameters in the 1 mm size range. Experiments were performed with air-diluent mixtures at about 0.101 MPa and 298 K, where carbon dioxide, helium, or xenon was separately used as the diluent gas. Results indicate that ambient gas transport properties play an important role in determining flammability and combustion behaviors including burning rates and radiant heat output historie...