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Spacelab Experiments on Combustion of Heptane/Hexadecane Droplets

Published on Jan 1, 2001in AIAA Journal1.95
· DOI :10.2514/2.1238
Benjamin D. Shaw1
Estimated H-index: 1
,
Bret D. Clark1
Estimated H-index: 1
,
Difei Wang1
Estimated H-index: 1
Cite
Abstract
Results are presented from experiments on reduced-gravity combustion of individual heptane/hexadecane droplets. Initial droplet diameters ranged from 0.25 to 5.2 mm, and initial hexadecane mass fractions in the droplets were 0.058, 0.10, 0.20, and 0.40. Most droplets were burned in cabin air on Spacelab with an ambient oxygen mole fraction of about 0.21 and a pressure of about 0.1 MPa. Data were also obtained for small (0.25-mm) droplets in a ground-based apparatus that provides simulated reduced gravity environments for droplet combustion experiments. Droplets in this apparatus were burned in high-temperature gases at 0.1 MPa. Data on flame contraction (i.e., the sudden contraction of the flame from droplet heating as the surface liquid mass fraction rapidly approaches unity) were used to estimate effective liquid species diffusivities that apply to these droplets. Significant differences in effective liquid species diffusivities were observed; these differences may be related to variations in internal circulation within the droplets, as well as possible variations in droplet temperatures. The Spacelab results indicate that flame extinction can be induced by flame contraction and that the occurrence of extinction depends on the initial droplet size. It was also observed that sooting and radiant heat losses varied significantly with initial droplet size in the Spacelab experiments. Sooting decreased as initial droplet sizes increased, whereas radiant heat loss rates varied in a complex fashion with the initial droplet size.
  • References (24)
  • Citations (9)
Cite
References24
Newest
Published on Dec 1, 2002in Microgravity Science and Technology1.97
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
M. J. Harrison1
Estimated H-index: 1
This paper describes analytical and experimental results related to the effects of support fibers on shapes of heptane/hexadecane mixture droplets (both burning and evaporating) in reduced gravity. The experimental results were obtained from large droplets (a few mm) investigated during the MSL-1 Flight of Spacelab. Theoretical (asymptotic) analyses are developed to predict droplet shapes. These analyses, which predict droplet shapes very well, illustrate important aspects of droplet shapes in a...
Published on Sep 8, 2005
W. A. Sirignano42
Estimated H-index: 42
,
Chris F. Edwards1
Estimated H-index: 1
1. Introduction 2. Isolated spherically symmetric droplet vaporization and heating 3. Convective droplet vaporization, heating, and acceleration 4. Multicomponent liquid droplets 5. Droplet behavior at near-critical, transcritical, and supercritical conditions 6. Droplet arrays and groups 7. Spray equations 8. Computational issues 9. Spray applications 10. Spray interactions with turbulence and vortical structures 11. Film vaporization 12. Stability of liquid streams.
Published on Jan 1, 2000in Combustion Science and Technology1.56
A.G. Chen1
Estimated H-index: 1
(UC Davis: University of California, Davis),
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis)
Abstract Results from reduced-gravity experiments on combustion of heptane/hexadecane mixture droplets and heptane droplets are presented. Initial droplet diameters were about 1 mm, and initial hexadecane mass fractions in the droplets were 0.6. The droplets were burned in air at 0.1 MPa. Attenuation of the beam from a diode laser was used to gain information on average soot volume fractions in the vicinities of the droplets. Results indicate that average soot volume fractions increased over the...
Published on Feb 1, 1999in Combustion and Flame4.12
Anthony J. Marchese23
Estimated H-index: 23
(Rowan University),
Frederick L. Dryer66
Estimated H-index: 66
(Princeton University),
Vedha Nayagam13
Estimated H-index: 13
Abstract Transient, spherically symmetric, combustion of single and multi-component liquid n-alkane droplets is numerically simulated with a model that includes gas phase detailed, multi-component molecular transport and complex chemical kinetics. A compact semi-detailed kinetic mechanism for n-heptane and n-hexadecane oxidation consisting of 51 species (including He, Ar, and N 2 ) and 282 reactions is used to describe the gas phase. Non-luminous, gas phase radiative heat transfer and conservati...
Published on Nov 1, 1998
Daniel L. Dietrich13
Estimated H-index: 13
,
Vedha Nayagan1
Estimated H-index: 1
+ 4 AuthorsR.O. Colantonio4
Estimated H-index: 4
Experimental results for the burning characteristics of fiber supported, liquid droplets in ambient Shuttle cabin air (21% oxygen, 1 bar pressure) were obtained from the Glove Box Facility aboard the STS-94/MSL-1 mission using the Fiber Supported Droplet Combustion - 2 (FSDC-2) apparatus. The combustion of individual droplets of methanol/water mixtures, ethanol, ethanol/water azeotrope, n-heptane, n-decane, and n-heptane/n-hexadecane mixtures were studied in quiescent air. The effects of low vel...
Published on Jun 1, 1998in Combustion and Flame4.12
I. Aharon1
Estimated H-index: 1
(UC Davis: University of California, Davis),
B.D. Shaw2
Estimated H-index: 2
(UC Davis: University of California, Davis)
Abstract Experiments on combustion of heptane/hexadecane mixture droplets were conducted in a reduced-gravity environment. Initial droplet diameters ranged from 0.47 to 1.5 mm, and initial hexadecane mass fractions ranged from 0.05 to 0.4. The ambient gas was O 2 /He (with O 2 mole fractions of 0.3 and 0.5), or atmospheric air, and pressures were varied from 0.033 to 0.3 MPa (abs). A previous asymptotic theory was extended to allow data on flame contractions to be used to estimate liquid species...
Published on Jan 1, 1998in AIAA Journal1.95
Vedha Nayagam13
Estimated H-index: 13
,
John B. Haggard5
Estimated H-index: 5
+ 4 AuthorsForman A. Williams48
Estimated H-index: 48
Results are presented from experiments on the combustion of freely floated n-heptane droplets in helium-oxygen environments conducted in Spacelab onboard the Space Shuttle Columbia during the first launch (STS-83) of the Microgravity Science Laboratory mission in April 1997. During this shortened flight, a total of eight droplets were burned successfully in nominally 300 K oxygen-helium atmospheres having oxygen mole fractions of 25, 30, and 35% at a total pressure of 1 atm. Initial droplet size...
Published on Mar 1, 1997in Combustion Science and Technology1.56
Anthony J. Marchese23
Estimated H-index: 23
(Princeton University),
Frederick L. Dryer66
Estimated H-index: 66
(Princeton University)
The effect or radiative heat loss from isolated droplet flames is usually assumed to be negligible. For the small droplet sizes studied in most isolated droplet combustion experiments conducted to dale (< 1.0 mm), this assumption has been shown to be reasonable. For example, by neglecting radiation, a detailed numerical model accurately predicts the burning rate, flame position and extinction diameter for 1 millimeter-sized methanol/waler droplets. However, recent space-based 3 to 5 millimeter m...
Published on Mar 1, 1996in Combustion Science and Technology1.56
D. F. Wang2
Estimated H-index: 2
(UC Davis: University of California, Davis),
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis)
Abstract Experimental results are presented on combustion of freely-falling droplets in an apparatus that promotes spherical symmetry. Design of the apparatus is based upon the principle that gravitation-ally-induced pressure gradients in gases may be significantly reduced by accelerating the gases with properly-contoured tubes. Droplets travelling with the gases experience substantially reduced forced-convective and buoyant (gravitational) flow effects, strongly promoting spherically symmetrica...
Cited By9
Newest
Published on Dec 1, 2018in AIAA Journal1.95
C. L. Vang (UC Davis: University of California, Davis), B. D. Shaw (UC Davis: University of California, Davis)
Combustion experiments on heptane–hexadecane mixture droplets were conducted onboard the International Space Station. The ambient consisted of oxygen mixed with either helium or nitrogen at 1 atm. Initial droplet diameters were in the 1.7–4.8 mm range with initial heptane mass fractions of 0.95 or 0.80. Because of limitations on resources, only fiber-supported experiments were possible. Vaporization of the more volatile fuel component (heptane) was favored during the droplet combustion process, ...
Published on Jul 1, 2015in Microgravity Science and Technology1.97
C. L. Vang1
Estimated H-index: 1
(UC: University of California),
Benjamin D. Shaw13
Estimated H-index: 13
(UC: University of California)
Results from International Space Station experiments on combustion of n-propanol/glycerol droplets are reported. The initial n-propanol mass fraction was 0.95 and droplets had initial diameters in the 2 – 5 mm range. Some droplets were fiber supported while others were free floating, and the environment was either an oxygen/nitrogen mixture at 1 atm or an oxygen/helium mixture at pressures of 1 and 3 atm. The droplets burned in a multi-stage manner where n-propanol was preferentially evaporated ...
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 Jul 1, 2014in Combustion and Flame4.12
Inkant Awasthi2
Estimated H-index: 2
(NU: University of Nebraska–Lincoln),
Daniel N. Pope9
Estimated H-index: 9
(UMN: University of Minnesota),
George Gogos17
Estimated H-index: 17
(NU: University of Nebraska–Lincoln)
Abstract Results are presented from transient numerical simulations of combustion of an isolated heptane (n- C 7 H 16 ) droplet in nearly quiescent ambient air. The focus is on the effects of environment temperature and droplet size on the combustion characteristics. Droplet sizes range from 10 μm to 1 mm, environment temperatures range from 800 K to 1600 K, and pressure is 1 atm. The results show that ignition delay times have a very moderate dependence on droplet diameter. With an increase in ...
Published on Jun 3, 2013in Combustion Science and Technology1.56
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
D. F. Wang2
Estimated H-index: 2
(UC Davis: University of California, Davis)
Flame extinction of n-heptane, n-decane, and n-hexadecane droplets freely falling through hot gases from a flat flame burner was investigated. Initial droplet diameters were in the range 270–285 µm. The hot gases from the flat flame burner were injected into straight and contoured flow tubes, providing flow environments that had various degrees of convection. Transport properties were modified through inert gas substitution as an efficient means of adjusting both quasisteady burning rates and ex...
Published on Jan 1, 2013
Alberto Cuoci27
Estimated H-index: 27
,
Alessio Frassoldati34
Estimated H-index: 34
+ 1 AuthorsE. Ranzi49
Estimated H-index: 49
Published on Dec 1, 2012in Combustion and Flame4.12
Vedha Nayagam13
Estimated H-index: 13
,
Daniel L. Dietrich13
Estimated H-index: 13
(Glenn Research Center)
+ 2 AuthorsForman A. Williams48
Estimated H-index: 48
(UCSD: University of California, San Diego)
Abstract Experimental observations of anomalous combustion of n-heptane droplets burning in microgravity are reported. Following ignition, a relatively large n-heptane droplet first undergoes radiative extinction, that is, the visible flame ceases to exist because of radiant energy loss. But the droplet continues to experience vigorous vaporization for an extended period according to a quasi-steady droplet-burning law, ending in a secondary extinction at a finite droplet diameter, after which a ...
Published on Oct 1, 2004in International Journal of Heat and Mass Transfer4.35
V. Dee1
Estimated H-index: 1
(UC Davis: University of California, Davis),
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis)
Abstract Reduced-gravity experiments on combustion of propanol–glycerol mixture droplets were performed. Droplets were initially about 1 mm in diameter with initial glycerol mass fractions of 0, 0.05 and 0.2. All experiments were in air at standard temperature and pressure. Experiments showed flame contractions, and data on burning rates and onset times for flame contraction allowed effective species diffusivities to be estimated. Comparison of the experiments with computational modeling suggest...
Published on Dec 1, 2002in Microgravity Science and Technology1.97
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
M. J. Harrison1
Estimated H-index: 1
This paper describes analytical and experimental results related to the effects of support fibers on shapes of heptane/hexadecane mixture droplets (both burning and evaporating) in reduced gravity. The experimental results were obtained from large droplets (a few mm) investigated during the MSL-1 Flight of Spacelab. Theoretical (asymptotic) analyses are developed to predict droplet shapes. These analyses, which predict droplet shapes very well, illustrate important aspects of droplet shapes in a...