Effects of Ambient Air Composition on Flame Temperature and Soot Formation in Intermittent Spray Combustion

2009 ◽  
Author(s):  
Akihiko Azetsu ◽  
Hiroaki Ito
Keyword(s):  
Soot Formation ◽  
Flame Temperature ◽  
Ambient Air ◽  
Spray Combustion

Evaluation of Soot Production Near a Cold Surface for an Impinged Diesel Spray Combustion

2020 ◽  
Author(s):  
Zhihao Zhao ◽  
Le Zhao ◽  
Seong-Young Lee
Keyword(s):  
Mass Fraction ◽  
Internal Combustion Engines ◽  
Soot Formation ◽  
Leading Edge ◽  
Ambient Air ◽  
Diesel Spray ◽  
Spray Combustion ◽  
Ambient Conditions ◽  
Cold Surface ◽  
Soot Mass

Abstract Spray impingement in internal combustion engines has received great attentions. Such a phenomenon is especially important for diesel spray because the spray and combustion characteristics are significantly altered by the impingement. In this study, numerical investigations of impinged reacting spray jets in a constant volume combustion chamber were performed to understand the spray and flame structure under high pressure and high temperature conditions. The 3-D computational fluid dynamics (CFD) CONVERGE code was selected as the numerical tool to perform Large-eddy simulations (LES) to understand the process of spray combustion-wall interaction. CFD models were validated against experimental results in terms of spray penetration and ignition delay at inert and reacting spray conditions. The temperature and soot mass fraction profiles near the impinging plate were investigated for 900 and 1000 K ambient conditions. It was found that soot mass fraction is generally increased near the impinging plate as the temperature is decreased. The heat transfer from the flame to the plate makes the temperature close to the wall more favorable for soot formation. A dense soot core was observed at the leading edge when the injection was still happening because the vortex there took the opportunity from existing burned gas to new fuel to meet the ambient air. A soot layer was observed stick on the wall as the air was hard to entrain the flame all the way to the plate side.

A Numerical Study for the Effect of Liquid Film on Soot Formation of Impinged Spray Combustion

2021 ◽  
Author(s):  
Zhihao Zhao ◽  
Xiucheng Zhu ◽  
Le Zhao ◽  
Meng Tang ◽  
Seong-Young Lee
Keyword(s):  
Liquid Film ◽  
Soot Formation ◽  
Numerical Study ◽  
Spray Combustion

Spray Combustion Characteristics of Single/Multi-Component Surrogate Fuel for Aviation Kerosene

2022 ◽  
Author(s):  
Wenjin Qin ◽  
Dengbiao Lu ◽  
Lihui Xu
Keyword(s):  
Soot Formation ◽  
Mean Field ◽  
Combustion Characteristics ◽  
Spray Combustion ◽  
Aviation Kerosene ◽  
Eddy Simulation ◽  
Air Mixing ◽  
Flow Field Characteristics ◽  
Lift Off ◽  
Surrogate Fuel

Abstract In this research, n-dodecane and JW are selected as single and multi-component surrogate fuel of aviation kerosene to study the Jet-A spray combustion characteristics. The spray combustion phenomena are simulated using large eddy simulation coupled with detailed chemical reaction mechanism. Proper orthogonal decomposition method is applied to analyze the flow field characteristics, and the instantaneous velocity field are decomposed into four parts, namely the mean field, coherent field, transition field and turbulent field, respectively. The four subfields have their own characteristics. In terms of different fuels, JW has a higher intensity of coherent structures and local vortices than n-dodecane, which promotes the fuel-air mixing and improves the combustion characteristics, and the soot formation is significantly reduced. In addition, with the increase of initial temperature, the combustion is more intense, the ignition delay time is advanced, the flame lift-off length is reduced, and soot formation is increased accordingly.

PAHs and Soot Emissions in Oxygenated Ethylene Diffusion Flames at Elevated Pressures

2018 ◽  
Author(s):  
Krishna C. Kalvakala ◽  
Suresh K. Aggarwal
Keyword(s):  
Diffusion Flames ◽  
Soot Formation ◽  
Computational Study ◽  
Mixture Fraction ◽  
Flame Temperature ◽  
Primary Objective ◽  
Soot Emission ◽  
Elevated Pressures ◽  
Polycyclic Aromatic ◽  
Soot Emissions

Operating combustion systems at elevated pressures has the advantage of improved thermal efficiency and system compactness. However, it also leads to increased soot emission. We report herein a computational study to characterize the effect of oxygenation on PAHs (Polycyclic Aromatic Hydrocarbons) and soot emissions in ethylene diffusion flames at pressures 1–8atm. Laminar oxygenated flames are established in a counterflow configuration by using N2 diluted fuel stream along with O2 enriched oxidizer stream such that the stoichiometric mixture fraction (ζst) is varied, but the adiabatic flame temperature is not materially changed. Simulations are performed using a validated fuel chemistry model and a detailed soot model. The primary objective of the study was to expand the fundamental understanding of PAH and soot formation in oxygenated flames at elevated pressures. At a given pressure, as the level of oxygenation (ζst) is increased, we observe a significant reduction in PAHs (benzene and pyrene) and consequently in soot formation. Further, at a fixed ζst, as pressure is increased, it leads to increased benzene and pyrene formation, and thus increased soot emission. The reaction path analysis indicates that this can be attributed to the fact that at higher pressures, the C2/C4 path becomes more significant for benzene formation compared to the propargyl recombination path.

Simultaneous Imaging of OH* Chemiluminescence and Flame Luminosity of Diesel and Biodiesel Spray Combustion

2011 ◽  
Author(s):  
Ji Zhang ◽  
Tiegang Fang
Keyword(s):  
Ambient Temperature ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Soot Formation ◽  
Combustion Process ◽  
Spray Combustion ◽  
Chemiluminescence Intensity ◽  
High Temperature Reaction ◽  
The Impact

The research on the spray combustion of diesel and biodiesel is vital to the understanding of emission formation and optimal utilization of fuel. This paper studies the biodiesel and diesel spray combustion in a constant volume chamber under different simulated diesel engine conditions. The ambient temperature at fuel injection varied from 800K to 1200K, while the ambient oxygen concentration was maintained at 21%. Simultaneous high speed imaging of OH* chemiluminescence and flame luminosity was employed to visualize the whole combustion process. Heat release rate was analyzed based on the measured combustion pressure. The apparent heat release rate analysis shows that biodiesel has a shorter ignition delay time than diesel, and biodiesel has a smaller cumulative heat release value due to its lower heating value. The overlaying image of OH* chemiluminescence and flame luminosity clearly identifies the high temperature reaction regions and soot formation regions. The line-of-sight images agree with the published observation that the hydroxyl radical is formed on the lean side of the flame edge. Decreasing ambient temperature greatly reduces the OH* chemiluminescence intensity of the diesel combustion, while the impact is smoother and milder for biodiesel combustion. Biodiesel shows a significantly lower level of flame luminosity than diesel under all conditions. These combined observations lead to a speculation that the soot oxidation process may serve as an important contributor to OH* chemiluminescence intensity for late stage combustion, and biodiesel shows a tendency to produce less soot than diesel under the investigated conditions.

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