Observation of sooting behavior in an emulsion droplet flame by planar laser light scattering in microgravity

Tsue, Mitsuhiro; Segawa, Daisuke; Kadota, T.; Yamasaki, Hiroshi

doi:10.1016/s0082-0784(96)80342-0

Cited by 26 publications

(14 citation statements)

References 8 publications

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“…Other visualization methods can be used to infer the symmetry of droplet burning in microgravity. For example, probing the lower hemisphere around a suspended dodecane droplet using a planar laser scattering technique, 18 with initial droplet diameter around 1000 l m and a ber diameter of 250 l m (giving d 0 / d ber = 4), indicated evidence of a spherical soot pattern for the hemisphere that could be visualized. This result is consistent with the photographs in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The patterns and transport of soot aggregates around the burning droplets were recorded using high-speed cine photography with back lighting set to emphasize the characteristics of the soot shell. More quantitative methods such as those involving laser diagnostics 3,18 have also been used to study soot inside suspended droplet ames in microgravity,but such methods were not used here as they would not have provided substantiallymore information relevant to this study. Frame by frame analysis of the motion picture sequences provided data on the evolutionof droplet diameter during the burning process.…”

Section: Introductionmentioning

confidence: 99%

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Soot Patterns Around Suspended n-Heptane Droplet Flames in a Convection-Free Environment

Avedisian

Jackson

2000

Journal of Propulsion and Power

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The trapping and transport of soot aggregates between a burning suspended droplet and its ame in a convectionfree (microgravity) environment are discussed. Many researchers have utilized the suspended droplet method for studying droplet combustion in microgravity where the intent is to create a spherically symmetric burning process. In the ideal case, soot particles are trapped in a spherical shell-like structure between the droplet and the ame. Results presented show that the ber support can prevent the formation of spherical soot shells if the ber diameter is large relative to the droplet diameter are presented for suspended droplets burning in microgravity. The effect of the ber is conjectured to arise by its in uence on the gas-phase temperature and Stefan velocity elds around the burning droplet. Droplets with initial diameters between 700 and 850 µ m were mounted on silica quartz bers with diameters of 57, 110, 220, and 330 µ m, and the droplets were ignited with sparks generated from two retractable electrode pairs. Photographic records of the burning process show soot aggregates inside the ame forming a shell-like structure, which evolves into a nonsymmetric con guration due to a nonsymmetric distribution of thermophoretic and Stefan drag forces around the droplet caused by ame/ ber interactions. For the four ber diameters examined, the burning rates (extracted over a large portion of burning process) appear to approach the free droplet value as the ratio of the initial droplet diameter to the ber diameter increases.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Soot Patterns Around Suspended n-Heptane Droplet Flames in a Convection-Free Environment

Avedisian

Jackson

2000

Journal of Propulsion and Power

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“…Nazha and Crookes [10] reported that the high-equivalence-ratio region that is present in emulsified fuel spray disappears as a result of the improved mixing of fuel vapor 21 with combustion air, which suppresses soot formation. Tue et al [11] also reported that the enhanced mixing caused by the puffing behavior decreases the volume of the sooting region.…”

Section: Emissions From the Combustion Furnace Incorporating The Rapimentioning

confidence: 96%

Rapid emulsification of a fuel–water rapid internal mixing injector for emulsion fuel combustion

Arshad¹,

Nada²,

Kidoguchi³

et al. 2018

Preprint

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In this study, a fuel-water rapid internal mixing injector capable of reducing emissions from combustion furnaces operating under high load conditions was developed. Employing this injector allows the injection of a fresh emulsified fuel mixture without requiring surfactants or additional processing equipment. The aim of the present study was to investigate the emulsification, atomization, and emission performance of the injector when using soybean oil as a model high-viscosity fuel from a renewable source. Successful emulsification was observed in the mixing chamber over a wide range of water content ratios up to 0.5, under which a water-in-oil emulsion was discharged from the injector. As the water content ratio was increased, the Sauter mean diameter of the droplets in the spray increased. This is a result of the decrease in the mass flow ratio of atomizing gas to liquid and the increase in the viscosity of the fuel emulsion. Although the emulsification of the base fuel resulted in the discharge of large droplets, the results showed that the nitrogen oxide and particulate matter emissions from a combustion furnace incorporating the injector were found to be reduced simultaneously following the introduction of water even under a high combustion load. Highlightso No surfactant is required in the fuel-water rapid internal mixing injector.o Successful emulsification was observed in the mixing chamber.o The NOx and soot emissions were reduced simultaneously.

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“…al. [10] and Watanbe et al, [11], gave a more specific definition for droplet puffing, that is the process of vapour jet liberation form the surface of the multicomponent fuel droplet. This vapour jet is usually filled with finely small sub-droplets of the dispersed phase.…”

Section: Introductionmentioning

confidence: 99%

Multicomponent fuel droplet combustion investigation using magnified high speed backlighting and shadowgraph imaging

Faik

Yang

2018

Fuel

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The liquid-phase processes occurring during fuel droplet combustion are important in deciding the behaviour of the overall combustion process, especially, for the multicomponent fuel droplets. Hence, understanding these processes is essential for explaining the combustion of the multicomponent fuel droplet. However, the very fast combustion of the too small fuel droplet makes experimental investigation of these processes uneasily affordable. In the present work, a high speed backlighting and shadowgraph imaging of the multicomponent fuel droplet combustion including liquid-phase dynamics are performed. Two categories of multicomponent fuelsin which diesel is the base fuelare prepared and utilized. The first category is biodiesel/diesel and bioethanol/diesel blends, while the second category is the water-in-diesel and diesel-in-water emulsions. Specific optical setups are developed and used for tracking droplet combustion. The first setup is associated with the backlighting imaging with the resulting magnification of the droplet images being 30 times the real size. The second optical setup is used for shadowgraph imaging, with the resulting magnification being 10 times the real size. Using these setups, spatial and temporal tracking of nucleation, bubble generation, internal circulation, puffing, microexplosion, and secondary atomization during the combustion of isolated multicomponent fuel droplets are performed. Spatial and temporal tracking of the sub-droplets generated by secondary atomization, and their subsequent combustion, in addition to their overall lifetimes have also been performed. Accordingly, a comparison of the burning rate constant between the parent droplet and the resulting sub-droplets is carried out. The rate of droplet secondary atomization is higher than those obtained by relatively low imaging rate. Additionally, it is shown that during a large portion of its entire lifetime, the droplet geometry has been affected by combustion significantly.

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Observation of sooting behavior in an emulsion droplet flame by planar laser light scattering in microgravity

Cited by 26 publications

References 8 publications

Soot Patterns Around Suspended n-Heptane Droplet Flames in a Convection-Free Environment

Soot Patterns Around Suspended n-Heptane Droplet Flames in a Convection-Free Environment

Rapid emulsification of a fuel–water rapid internal mixing injector for emulsion fuel combustion

Multicomponent fuel droplet combustion investigation using magnified high speed backlighting and shadowgraph imaging

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