Effects of Droplet Size and Air Preheating on Soot Formation in Turbulent Combustion of Liquid Fuel

2010 ◽  
Author(s):  
Amirmahdi Ghasemi ◽  
Mohammad Moghiman ◽  
Seyed Mohammad Javadi ◽  
Naseh Hosseini
Keyword(s):  
Droplet Size ◽  
Liquid Fuel ◽  
Soot Formation ◽  
Control Volume ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Soot Emission ◽  
Fuel Droplet ◽  
Air Inlet ◽  
Spray Flames

The present study is concerned with the effect of fuel droplet size, air inlet preheating and air swirl number on complex soot process in a turbulent liquid-fuelled combustor. A hybrid Eulerian-Lagrangian method is employed to model the reactive flow-field inside the combustor. Equations governing the gas phase are solved by a control volume based semi-implicit iterative procedure while the time-dependent differential equations for each sizes of the fuel droplets are integrated by a semi-analytic method. The processes leading to soot consist of both formation and combustion. Soot formation is simulated using a two-step model while a finite rate combustion model with eddy dissipation concept is implemented for soot combustion. Also, mathematical models for turbulence, combustion, and radiation are used to take account the effects of these processes. Results reveal the significant influence of liquid fuel droplet size, air inlet temperatures and swirl numbers on soot emission from turbulent spray flames. The predictions show that reduction of spray droplet size and increases of air inlet temperature and swirl numbers considerably, increases soot emission from spray flames.

Effects of fuel droplet size on soot formation in spray flames formed in a laminar counterflow

2011 ◽  
Vol 158 (12) ◽  
pp. 2559-2568 ◽  
Author(s):  
Jun Hayashi ◽  
Hiroaki Watanabe ◽  
Ryoichi Kurose ◽  
Fumiteru Akamatsu
Keyword(s):  
Droplet Size ◽  
Soot Formation ◽  
Fuel Droplet ◽  
Spray Flames

scholarly journals Study on Soot Formation in Spray Flames (Effect of Droplet Size Distribution)

2008 ◽  
Vol 74 (738) ◽  
pp. 429-437
Author(s):  
Jun HAYASHI ◽  
Fumiteru AKAMATSU ◽  
Chulju AHN ◽  
Takehiko SEO ◽  
Hiroaki WATANABE ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Soot Formation ◽  
Droplet Size Distribution ◽  
Spray Flames

CFD Analysis of Scramjet Combustor with Non-Premixed Turbulence Model Using Ramp Injector

2014 ◽  
Vol 555 ◽  
pp. 18-25 ◽  
Author(s):  
Krishna Murari Pandey ◽  
Sukanta Roga
Keyword(s):  
Supersonic Combustion ◽  
Maximum Temperature ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Reacting Flow ◽  
Complete Combustion ◽  
Scramjet Combustor ◽  
Air Inlet ◽  
Fuel Jet ◽  
Combustion Of Hydrogen

This paper presents the supersonic combustion of hydrogen using strut injector along with two-dimensional turbulent non-premixed combustion model with air inlet temperature of 750 0k and vitiated Mach number of 2. In this process, a PDF approach is created and this method needs solution to a high dimensional PDF transport equation. As the combustion of hydrogen fuel is injected from the strut injector, it is successfully used to model the turbulent reacting flow field. It is observed from the present work that, the maximum temperature of 2096 0k occurred in the recirculation area which is produced due to shock wave-expansion and the fuel jet losses concentration and after passing successively through such areas, temperature decreased slightly along the axis. From the maximum mass fraction of OH, it is observed that there is very little amount of OH around 0.0017 were found out after combustion. By providing strut injector, expansion wave is created which causes the proper mixing between the fuel and air that results in complete combustion.

Numerical Investigation of Soot Formation in Laminar Ethylene-Air Diffusion Flames

2007 ◽  
Author(s):  
Massimiliano Di Domenico ◽  
Peter Gerlinger ◽  
Manfred Aigner
Keyword(s):  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Formation Rate ◽  
Soot Volume Fraction ◽  
Transport Equations ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Elementary Reactions ◽  
Air Diffusion

In this work a new soot formation model is used to predict temperature, species and soot concentrations in laminar ethylene-air diffusion flames. The gas-phase chemistry is described by elementary reactions with transport equations solved for any species. The chemical paths yielding to soot are modeled by a sectional approach for Polycyclic Aromatic Hydrocarbons (PAHs). Soot dynamics is described by a two-equation model for soot mass fraction and particle number density. Phenomena like nucleation, growth and oxidation have been included both for PAHs and soot. Moreover, PAH-PAH and PAH-soot collisions are taken into account. Species, PAH and soot transport equations are implemented in the in-house DLR-THETA CFD code. The laminar, ethylene-air diffusion flame investigated experimentally by McEnally and coworkers (2000) is simulated in order to validate the model. An analysis of the main flame’s features as well as the interaction between them and the soot chemistry will be given. A qualitative correlation between local stoichiometric values and soot formation rate is assessed. In order to study the sensitivity of the combustion model to simulation parameters like the inlet temperature and kinetic mechanism, additional simulations are performed. Results are also compared with experimental data in terms of temperature, species mole fractions and soot volume fraction axial profiles.

scholarly journals Microencapsulation ofβ-Carotene by Spray Drying: Effect of Wall Material Concentration and Drying Inlet Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Luiz C. Corrêa-Filho ◽  
Maria M. Lourenço ◽  
Margarida Moldão-Martins ◽  
Vítor D. Alves
Keyword(s):  
Antioxidant Activity ◽  
Spray Drying ◽  
Encapsulation Efficiency ◽  
Fruits And Vegetables ◽  
Wall Material ◽  
Inlet Temperature ◽  
Carotene Content ◽  
Arabic Gum ◽  
Air Inlet ◽  
Adverse Environmental Conditions

Carotenoids are a class of natural pigments found mainly in fruits and vegetables. Among them,β-carotene is regarded the most potent precursor of vitamin A. However, it is susceptible to oxidation upon exposure to oxygen, light, and heat, which can result in loss of colour, antioxidant activity, and vitamin activity. Thus, the objective of this work was to study the microencapsulation process ofβ-carotene by spray drying, using arabic gum as wall material, to protect it against adverse environmental conditions. This was carried out using the response surface methodology coupled to a central composite rotatable design, evaluating simultaneously the effect of drying air inlet temperature (110-200°C) and the wall material concentration (5-35%) on the drying yield, encapsulation efficiency, loading capacity, and antioxidant activity. In addition, morphology and particles size distribution were evaluated. Scanning electron microscopy images have shown that the particles were microcapsules with a smooth surface when produced at the higher drying temperatures tested, most of them having a diameter lower than 10μm. The conditions that enabled obtaining simultaneously arabic gum microparticles with higherβ-carotene content, higher encapsulation efficiency, and higher drying yield were a wall material concentration of 11.9% and a drying inlet temperature of 173°C. The systematic approach used for the study ofβ-carotene microencapsulation process by spray drying using arabic gum may be easily applied for other core and wall materials.

Rough Air-Soft Elastohydrodynamic Lubrication

2013 ◽  
Vol 420 ◽  
pp. 30-35
Author(s):  
Khanittha Wongseedakaew ◽  
Jesda Panichakorn
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Multilevel Methods ◽  
Inlet Temperature ◽  
Film Pressure ◽  
Air Inlet ◽  
Air Film

This paper presents the effects of rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material under the effect of air molecular slip. The time independent modified Reynolds equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness, modulus of elasticity and air inlet temperature are examined. The simulation results showed surface roughness has effect on film thickness but it little effect to air film pressure. When the amplitude of surface roughness and modulus of elasticity increased, the air film thickness decreased but air film pressure increased. However, the air inlet temperature increased when the air film thickness increased.

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