The Combustion Characteristics of n-Decane/Iso-Octane/Toluene Mixture and Jet-A Fuel Droplets in the Absence of Convection

2011 ◽  
Author(s):  
Yu-Cheng Liu ◽  
Anthony J. Savas ◽  
C. Thomas Avedisian
Keyword(s):  
Burning Rate ◽  
Droplet Diameter ◽  
Mixture Fraction ◽  
Combustion Characteristics ◽  
Aviation Fuel ◽  
Ternary Blend ◽  
Transportation Fuel ◽  
Spherical Droplet ◽  
Burning Process ◽  
Fuel Droplets

This study examines the extent to which a ternary mixture of n-decane/iso-octane/toluene in the specific mixture fraction of 42.67/33.02/24.31 (mole fraction), respectively, can replicate the droplet burning characteristics of an aviation fuel, Jet-A (designated by the Air Force as “POSF4658”). Experiments were carried out to examine the droplet combustion characteristics in an environment which minimizes convection to promote spherical symmetry in the burning process. The evolution of droplet diameter, burning rate and flame and soot stand-off ratios were compared to Jet-A to evaluate the potential of this ternary to serve as a Jet-A surrogate regarding the droplet burning process. The results show that the ternary blend has a shorter transient droplet heating period than Jet-A and it closely replicates the evolution of droplet diameter and burning rate. The burning rates for these two fuels are close at the end of burning, and flame and soot standoff ratios for the ternary are also reasonably close to those of Jet-A. The results also suggest that the spherical droplet flame configuration can be a useful tool to evaluate the extent to which a mixture of single component fuels may serve as a surrogate of a real transportation fuel.

Effects of droplet diameter on instantaneous burning rate of isolated fuel droplets in argon-rich or carbon dioxide-rich ambiences under microgravity

2013 ◽  
Vol 34 (1) ◽  
pp. 1601-1608 ◽  
Author(s):  
Shinji Nakaya ◽  
Kotaro Fujishima ◽  
Mitsuhiro Tsue ◽  
Michikata Kono ◽  
Daisuke Segawa
Keyword(s):  
Carbon Dioxide ◽  
Burning Rate ◽  
Droplet Diameter ◽  
Fuel Droplets

Effects of Initial Diameter on Burning of Nonane Droplets in a Non-Buoyant and Buoyant Ambience: Burning Rate, Soot Formation and Flame Structure

2001 ◽  
Author(s):  
J. H. Bae ◽  
C. T. Avedisian
Keyword(s):  
Burning Rate ◽  
Droplet Size ◽  
Soot Formation ◽  
Droplet Diameter ◽  
Flame Structure ◽  
Large Droplet ◽  
Droplet Combustion ◽  
Small Droplet ◽  
Burning Process ◽  
Initial Droplet

Abstract The results from nonane droplet combustion experiments conducted at 1g and μg are analyzed and compared in the following aspects: the burning rate, soot formation, flame structure. By varying the initial droplet diameter, we observe and discuss the effect of Do on droplet burning. The μg experiments were performed in a drop tower and a drag shield was used to create a low buoyant environment All experiments were fiber-supported and used the same experimental instruments. The droplet size between 0.40 to 0.95mm was examined in the experiments. Results showed that droplet burning is nonlinear in both a buoyant and a non-buoyant environment for the initial droplet diameters examined. Soot formation, which is influenced by Do may strongly affect the droplet burning process in both environments. The large droplet produces more soot and bums slowly whereas the small droplet bums fast because there is less soot.

Surrogate Fuel Development: The Role of Droplet Burning

2008 ◽  
Author(s):  
C. Thomas Avedisian
Keyword(s):  
Burning Rate ◽  
Liquid Fuel ◽  
Performance Metrics ◽  
Aviation Fuel ◽  
Spherical Droplet ◽  
One Dimensional ◽  
Surrogate Fuels ◽  
Diameter Droplet ◽  
Surrogate Fuel

This paper examines the role which droplet combustion can play in the development of liquid surrogate fuels. The spherical droplet flame configuration is the canonical configuration of liquid fuel combustion with its one dimensional transport process and spherical soot cloud that surrounds the droplet during burning, thus making it a useful perspective from which to develop a surrogate fuel. The liquid fuel burning process includes a number of characteristic parameters which can serve as useful benchmarks against which to compare performance of a surrogate and real fuel. For sprays and droplets these include burning rate, droplet extinction diameter, droplet number density, mean droplet size and soot emissions. At the same time, not all performance metrics of a real fuel can be replicated by a surrogate. An example is given for the case of a highly sooting aviation fuel (JP8) mixed with an alcohol (hexanol). It is shown that on one hand the spherically symmetric droplet burning rate of the JP8+hexanol blend is almost the same as pure hexanol, thus suggesting hexanol as a surrogate for the mixture in terms of burning rate. On the other, sooting propensities are significantly different for hexanol and the mixture.

scholarly journals Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1229
Author(s):  
Hongtao Zhang ◽  
Zhihua Wang ◽  
Yong He ◽  
Jie Huang ◽  
Kefa Cen
Keyword(s):  
Burning Rate ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Ambient Pressure ◽  
Interactive Effects ◽  
Propagation Time ◽  
High Speed Camera ◽  
Single Droplet ◽  
Fuel Droplets ◽  
Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

Spray and Emission Characteristics Near Lean Blow Out in a Counter-Swirl Stabilized Gas Turbine Combustor

2006 ◽  
Author(s):  
Jonathan A. Colby ◽  
Suresh Menon ◽  
Jechiel Jagoda
Keyword(s):  
Droplet Diameter ◽  
Reacting Flow ◽  
Gas Turbine Combustor ◽  
Complete Combustion ◽  
Fuel Droplets ◽  
Phase Velocities ◽  
Fuel Jet ◽  
Key Factor ◽  
Flow Features ◽  
Initial Droplet Size

An experimental study of a single, swirl cup burner is carried out to improve understanding of the lean reacting flow field near idle conditions for an annular spray combustor. The counter-swirler is mounted horizontally in a trapezoidal cross-section combustor with quartz plate walls. Liquid fuel, Jet-A, is initially atomized using a simplex nozzle, and then a designed re-atomization occurs from the swirler hardware. Measurements of non-reacting and reacting gas phase velocities enable the direct comparison of critical flow features at various power settings. Droplet diameter and exhaust composition measurements confirm that the initial droplet size is a key factor in emission levels. Smaller droplets in the spray periphery tend to evaporate and burn premixed, while larger droplets in the spray core convect downstream and burn with a sheath-type, non-premixed flame. The presence of small fuel droplets in the spray may ensure more complete combustion and improve combustor stability at lean, low power settings.

Effect of Nanoparticles on the Fuel Properties and Spray Performance of Aviation Turbine Fuel

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Kumaran Kannaiyan ◽  
Kanjirakat Anoop ◽  
Reza Sadr
Keyword(s):  
Surface Tension ◽  
Physical Properties ◽  
Droplet Diameter ◽  
Cone Angle ◽  
Aviation Fuel ◽  
Alumina Nanoparticles ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Breakup Length ◽  
Sheet Breakup

The influence of nanoparticles' dispersion on the physical properties of aviation fuel and its spray performance has been investigated in this work. To this end, the conventional Jet A-1 aviation fuel and its mixtures with alumina nanoparticles (nanofuel) at different weight concentrations are investigated. The key fuel physical properties such as density, viscosity, and surface tension that are of importance to the fuel atomization process are measured for the base fuel and nanofuels. The macroscopic spray features like spray cone angle and sheet breakup length are determined using the shadowgraph technique. The microscopic spray characteristics such as droplet diameter, droplet velocity, and their distributions are also measured by employing phase Doppler anemometry (PDA) technique. The spray performance is measured at two nozzle injection pressures of 0.3 and 0.9 MPa. The results show that with the increase in nanoparticle concentrations in the base fuel, the fuel viscosity and density increase, whereas the surface tension decreases. On the spray performance, the liquid sheet breakup length decreases with increasing nanoparticle concentrations. Furthermore, the mean droplet diameters of nanofuel are found to be lower than those of the base fuel.

Co-combustion Characteristics and Kinetics Behavior of Torrefied Sugarcane Bagasse and Lignite

2021 ◽  
Vol 10 (4) ◽  
pp. 737-746
Author(s):  
Ukrit Samaksaman ◽  
Kanit Manatura
Keyword(s):  
Thermogravimetric Analysis ◽  
Physicochemical Properties ◽  
Burning Rate ◽  
Sugarcane Bagasse ◽  
Combustion Characteristics ◽  
Firing Process ◽  
Combustion System ◽  
Heating Value ◽  
Kinetics Of ◽  
Derivative Thermogravimetry

The co-combustion characteristics and kinetics of torrefied sugarcane bagasse (TB), lignite (L), and their blended samples were experimentally investigated using thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG)based on the Coats-Redfern method for kinetic estimation.Their physicochemical properties were also investigated.Raw bagasse was thermally treated in a laboratory-scale torrefactor at 275 °C with a torrefaction time of 60 min under an inert nitrogen environment.Then, the torrefied bagasse was blended with Thai lignite as a co-fuel at ratios of 50:50 (TB50L50), 70;30(TB70L30), and 90:10 (TB90L10), respectively. Torrefaction improved the fuel properties and heating value of the raw bagasse as well as reducing the O/C and H/C ratios.In addition, the blending of torrefied bagasse with lignite improved the combustion behavior.The TGA and DTG results indicated that the ignition and burnout temperatures stepped downwards with different increasing ratios of torrefied bagasse.The co-combustion behavior at the maximum burning rate showed that the burnout temperatures of TB50L50, TB70L30, and TB90L10 were 532, 529, and 528 °C, respectively, indicating a slight decrease with an increasing torrefied bagasse blending ratio.These results were sufficient to provide comprehensive guidelines in terms of the design and operation of the combustion system for adding torrefied bagasse into the co-firing process.

Combustion Characteristics of Isolated Free-Falling Droplets of Jet A Blended With Ethanol and Butanol

2018 ◽  
Author(s):  
Álvaro Muelas ◽  
Pilar Remacha ◽  
Javier Ballester
Keyword(s):  
Gas Turbines ◽  
Alternative Fuels ◽  
Droplet Diameter ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Shell Size ◽  
Pure Ethanol ◽  
Promising Alternative ◽  
Burning Rates ◽  
Alcohol Mixtures

Recent studies on experimental gas turbines suggest that the addition of ethanol or butanol to Jet A are viable alternatives for reducing CO and NOx emissions while maintaining similar performance to that of pure Jet A. In light of this potential, experimental data regarding the burning characteristics of Jet A/ethanol and Jet A/butanol blends are required in order to better understand their combustion process. Following a previous study on Jet A/butanol droplet combustion, the scope has been extended in order to also include ethanol and a Jet A/ethanol mixture as well as to perform a more detailed characterization. In this work the combustion characteristics of Jet A, butanol, ethanol and their mixtures (20% vol. alcohol in kerosene) are presented for different test conditions. The evaluated combustion characteristics include droplet, flame and soot shell size evolutions, burning rates and image-based soot estimations. The influence of oxygen availability is also ascertained. The evolution of droplet diameter and burning rates for Jet A and its blends with both alcohols are very similar, whereas pure ethanol and butanol display more distinct behaviors. Soot indices are found to be quite different, with a clear reduction in the sooting propensity of the Jet A/alcohol mixtures when compared to neat kerosene. These results support the feasibility of kerosene-alcohol mixtures as promising alternative fuels with similar combustion characteristics, but with much lower sooting propensity than pure kerosene.

Experimental study on combustion characteristics of blended fuel pool fires

2019 ◽  
Vol 37 (3) ◽  
pp. 236-256 ◽  
Author(s):  
Xuehui Wang ◽  
Tiannian Zhou ◽  
Qinpei Chen ◽  
Junjiang He ◽  
Zheng Zhang ◽  
...  
Keyword(s):  
Volatile Component ◽  
Combustion Characteristics ◽  
Boiling Temperature ◽  
Flame Height ◽  
Distribution Model ◽  
Pool Fires ◽  
Burning Process ◽  
Fuel Blends ◽  
Axial Temperature ◽  
Blended Fuel

Liquid–vapor phase equilibrium theories are used to analyze boiling processes of blended fuel pool fires, and the results show that there are two boiling mechanisms (azeotropism and non-azeotropism) for blended fuels compared with single-component fuels. A series of pool fire experiments were conducted to investigate the combustion characteristics of blended fuel pool fires. The experimental results showed that the two boiling mechanisms have different effects on the burning process of the fuel blends. The boiling temperature and composition varied for the non-azeotropic blends during the burning process and remained steady for azeotropic blends. Furthermore, the boiling temperature of azeotropic blends is lower than that of its components and ranges from a specific temperature to the boiling point of the less volatile component. The flame radiant fraction of the azeotropic blend was also relatively constant during the burning process, whereas that of the non-azeotropic blend varied in different stages of the burning process. Heskestad’s flame height model and flame axial temperature distribution model are applicable for pool fires of azeotropic and non-azeotropic blends.

An Ignition Delay Study of Category A and C Aviation Fuel

2015 ◽  
Author(s):  
Kyungwook Min ◽  
Daniel Valco ◽  
Anna Oldani ◽  
Tonghun Lee
Keyword(s):  
Ignition Delay ◽  
Cetane Number ◽  
Test Chamber ◽  
Combustion Characteristics ◽  
Aviation Fuel ◽  
Jet Fuels ◽  
Fuel Blend ◽  
Auto Ignition ◽  
Alternative Aviation Fuels ◽  
Pressure Trace

Ignition delay of category A and C alternative aviation fuels have been investigated using a rapid compression machine (RCM). Newly introduced alternative jet fuels are not yet comprehensively understood in their combustion characteristics. Two of the category C fuels that will be primarily investigated in this study are Amyris Farnesane and Gevo Jet Fuel Blend. Amyris direct sugar to hydrocarbon (DSHC) fuel (POSF 10370) come from direct fermentation of bio feedstock sugar. Amyris DSHC is mainly composed of 2,6,10-trymethly dodecane, or farnesane. Gevo jet blend stock fuel is alcohol to jet (ATJ) fuel (POSF 10262) produced from bio derived butanol. Gevo jet blend stock is composed with iso-dodecane and iso-cetane, and has significantly low derived cetane number of 15. The experimental results are compared to combustion characteristics of conventional jet A fuels, including JP-8. Ignition delay, the important factor of auto ignition characteristic, is evaluated from pressure trace measured from the RCM at University of Illinois, Urbana-Champaign. The measurements are made at compressed pressure 20bar, intermediate and low compressed temperature, and equivalence ratio of unity and below. Direct test chamber charge method is used due to its reliable reproducibility of results. Compared to category A fuels, different combustion characteristics has been observed from category C fuels due to their irregular chemical composition.

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