Phenomenological Simulation of Non-Premixed Gas Jet Flames Including Soot Formation and Oxidation

2012 ◽  
Author(s):  
Ehsan Faghani ◽  
Steven N. Rogak
Keyword(s):  
Mass Fraction ◽  
Soot Formation ◽  
Equilibrium Composition ◽  
Gas Jet ◽  
Jet Flames ◽  
Engine Simulation ◽  
Soot Mass ◽  
Wide Range ◽  
Computationally Intensive ◽  
Energy Balances

A phenomenological model (called here “Slice Model”) has been developed to simulate non-premixed gas jet flames including soot formation in the domain. The Slice Model is based on the self-similarity solution of gas jets and forced to satisfy momentum, mass and energy balances in every cross section. The Slice Model can predict the velocity, mass fraction and temperature field of non-reacting and reacting jets over a wide range of changes in the jet parameters. A sub-model for soot formation based on Hiroyasu’ model is applied to predict soot formation in non-premixed flames. Cantera, an open-source chemical kinetics software, is integrated with the Slice Model to predict the temperature distribution (based on equilibrium composition) of reacting jets. The soot formation prediction of the Slice Model is compared with experimental data in the literature. For velocity, soot mass fraction and temperature, agreement with experiment is about as good as it is for the much more computationally intensive RANS CFD simulations. On this basis, the Slice Model is promising as the core of a non-premixed natural gas engine simulation package under development.

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.

scholarly journals Effect of exhaust gas recirculation composition on soot in ECN spray A conditions

2020 ◽  
Vol 75 ◽  
pp. 34 ◽  
Author(s):  
Chetankumar Patel ◽  
Camille Hespel ◽  
Tung Lam Nguyen ◽  
Fabrice Foucher ◽  
Christine Mounaïm-Rousselle
Keyword(s):  
Particulate Matter ◽  
Mass Fraction ◽  
Internal Combustion Engines ◽  
Soot Formation ◽  
Strong Impact ◽  
Advanced Combustion ◽  
Spray Flames ◽  
Soot Mass ◽  
Gas Recirculation ◽  
The Impact

Due to its strong impact on health, particulate matter is increasingly regulated by government emission standards for vehicles. As one of the sources of particulate matter is the soot produced by internal combustion engines, it remains a challenge to improve advanced combustion modes to reduce it. There is still, however, some lack of understanding about the formation and oxidation processes of soot, especially in “realistic” conditions, such as for example at high temperature and pressure conditions with or without the presence of exhaust gases. The objective of this study is to investigate soot formation in the case of n-Dodecane spray flames at conventional Diesel engine conditions generated in the New One Shot Engine by using diffused back-illumination extinction with different CO2 and water vapour contents. It was found that CO2 addition reduces the soot mass fraction if its volumetric concentration in ambient mixtures is at least 4.5% while 1% of water is sufficient to significantly reduce the soot mass fraction. The impact of the ambient mixture obtained in ECN spray A pre-burn vessels was also investigated to assess the accuracy against soot measurements available in the literature.

scholarly journals Numerical Investigation of Soot Formation in Turbulent Diffusion Flame With Strong Turbulence–Chemistry Interaction

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
B. Manedhar Reddy ◽  
Ashoke De ◽  
Rakesh Yadav
Keyword(s):  
Mass Fraction ◽  
Volume Fraction ◽  
Soot Formation ◽  
Mixture Fraction ◽  
Soot Volume Fraction ◽  
Turbulent Diffusion Flame ◽  
Flamelet Model ◽  
Soot Mass ◽  
One Step ◽  
Gas Flame

The present work is aimed at examining the ability of different models in predicting soot formation in “Delft flame III,” which is a nonpremixed pilot stabilized natural gas flame. The turbulence–chemistry interactions are modeled using a steady laminar flamelet model (SLFM). One-step and two-step models are used to describe the formation, growth, and oxidation of soot particles. One-step is an empirical model which solves the soot mass fraction equation. The two-step models are semi-empirical models, where the soot formation is modeled by solving the governing transport equations for the soot mass fraction and normalized radical nuclei concentration. The effect of radiative heat transfer due to gas and soot particulates is included using P1 approximation. The absorption coefficient of the mixture is modeled using the weighted sum of gray gases model (WSGGM). The turbulence–chemistry interaction effects on soot formation are studied using a single-variable probability density function (PDF) in terms of a normalized temperature or mixture fraction. The results shown in this work clearly elucidate the effect of radiation and turbulence–chemistry interaction on soot formation. The soot volume fraction decreases with the introduction of radiation interactions, which is consistence with the theoretical predictions. It has also been observed in the current work that the soot volume fraction is sensitive to the variable used in the PDF to incorporate the turbulence interactions.

Spatio-temporal profiling of cluster mass fraction in a pulsed supersonic gas jet by frequency-domain holography

2013 ◽  
Vol 114 (3) ◽  
pp. 034903 ◽  
Author(s):  
Xiaohui Gao ◽  
Alexey V. Arefiev ◽  
Richard C. Korzekwa ◽  
Xiaoming Wang ◽  
Bonggu Shim ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Mass Fraction ◽  
Gas Jet ◽  
Cluster Mass ◽  
Supersonic Gas Jet ◽  
Spatio Temporal

Prediction of Soot Formation Trends in Turbulent Kerosene-Air Diffusion Jet Flames With Elevated Operating Pressure

2017 ◽  
Author(s):  
Pravin Nakod ◽  
Saurabh Patwardhan ◽  
Ishan Verma ◽  
Stefano Orsino
Keyword(s):  
Environmental Protection Agency ◽  
Volume Fraction ◽  
Soot Formation ◽  
Mixture Fraction ◽  
Soot Volume Fraction ◽  
Operating Pressure ◽  
Jet Flames ◽  
Emission Standard ◽  
Radial Profiles ◽  
Air Diffusion

Emission standard agencies are coming up with more stringent regulations on soot, given its adverse effect on human health. It is expected that Environmental Protection Agency (EPA) will soon place stricter regulations on allowed levels of the size of soot particles from aircraft jet engines. Since, aircraft engines operate at varying operating pressure, temperature and air-fuel ratios, soot fraction changes from condition to condition. Computation Fluid Dynamics (CFD) simulations are playing a key role in understanding the complex mechanism of soot formation and the factors affecting it. In the present work, soot formation prediction from numerical analyses for turbulent kerosene-air diffusion jet flames at five different operating pressures in the range of 1 atm. to 7 atm. is presented. The geometrical and test conditions are obtained from Young’s thesis [1]. Coupled combustion-soot simulations are performed for all the flames using steady diffusion flamelet model for combustion and Mass-Brookes-Hall 2-equation model for soot with a 2D axisymmetric mesh. Combustion-Soot coupling is required to consider the effect of soot-radiation interaction. Simulation results in the form of axial and radial profiles of temperature, mixture fraction and soot volume fraction are compared with the corresponding experimental measured profiles. The results for temperature and mixture fraction compare well with the experimental profiles. Predicted order of magnitude and the profiles of the soot volume fraction also compare well with the experimental results. The correct trend of increasing the peak soot volume fraction with increasing the operating pressure is also captured.

Numerical Investigation on the Effect of Advanced Breakup Model on Spray Simulation of a Multi-Hole Injector

2018 ◽  
Author(s):  
Srinibas Tripathy ◽  
Sridhar Sahoo ◽  
Dhananjay Kumar Srivastava
Keyword(s):  
Mass Fraction ◽  
Gas Pressure ◽  
Gas Jet ◽  
Computational Time ◽  
Fuel Vapor ◽  
Computational Domain ◽  
Penetration Length ◽  
Spray Penetration ◽  
Ambient Gas ◽  
Vapor Mass

Computational fluid dynamics (CFD) plays a tremendous role in evaluating and visualizing the spray breakup, atomization and vaporization process. In this study, ANSYS Forte CFD tool was used to simulate the spray penetration length and spray morphology in a constant volume chamber at different grid size of a multi-hole injector. An unsteady gas jet model was coupled with Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) model for multi-hole spray simulation. The effect of CFD cell size and ambient gas pressure on spray penetration length and spray morphology of fuel vapor mass fraction were investigated for both KH-RT and KH-RT with the unsteady gas jet model. It is found that KH-RT with the unsteady gas jet model shows mesh independent spray penetration length and spray morphology of fuel vapor mass fraction as compared to KH-RT model. This can be explained by the Lagrangian-Eulerian coupling of axial droplet-gas relative velocity is modeled on the principle of unsteady gas jet theory instead of discretizing very fine grid to the computational domain. This reduces the requirement of fine mesh near the nozzle and allows larger time step during spray injection. It is also observed that at higher ambient gas pressure, an aerodynamic force between the droplet and gas intensifies which reduces the overall spray penetration length and fuel vapor mass. The distorted spray morphology of fuel vapor mass fraction was accurately predicted at high ambient gas pressure using the KH-RT with an unsteady gas jet model which results in mesh independent drag predictions. The use of advanced spray model results in the mesh size dependency reduction and accurate drag prediction with less computational time and faster accurate solutions over all conventional spray breakup models.

Hierarchical Multiscale Modeling of Tire–Soil Interaction for Off-Road Mobility Simulation

2019 ◽  
Vol 14 (6) ◽  
Author(s):  
Hiroki Yamashita ◽  
Guanchu Chen ◽  
Yeefeng Ruan ◽  
Paramsothy Jayakumar ◽  
Hiroyuki Sugiyama
Keyword(s):  
High Performance ◽  
Computational Models ◽  
Computational Cost ◽  
Interaction Model ◽  
High Fidelity ◽  
Wheel Load ◽  
Mobility Performance ◽  
Wide Range ◽  
Computationally Intensive ◽  
Soil Bin

A high-fidelity computational terrain dynamics model plays a crucial role in accurate vehicle mobility performance prediction under various maneuvering scenarios on deformable terrain. Although many computational models have been proposed using either finite element (FE) or discrete element (DE) approaches, phenomenological constitutive assumptions in FE soil models make the modeling of complex granular terrain behavior very difficult and DE soil models are computationally intensive, especially when considering a wide range of terrain. To address the limitations of existing deformable terrain models, this paper presents a hierarchical FE–DE multiscale tire–soil interaction simulation capability that can be integrated in the monolithic multibody dynamics solver for high-fidelity off-road mobility simulation using high-performance computing (HPC) techniques. It is demonstrated that computational cost is substantially lowered by the multiscale soil model as compared to the corresponding pure DE model while maintaining the solution accuracy. The multiscale tire–soil interaction model is validated against the soil bin mobility test data under various wheel load and tire inflation pressure conditions, thereby demonstrating the potential of the proposed method for resolving challenging vehicle-terrain interaction problems.

scholarly journals Self-Assembly of Temperature Sensitive Unilamellar Vesicles by a Blend of Block Copolymers in Aqueous Solution

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 63 ◽  
Author(s):  
Jong Dae Jang ◽  
Changwoo Do ◽  
Joona Bang ◽  
Young Soo Han ◽  
Tae-Hwan Kim
Keyword(s):  
Block Copolymers ◽  
Hydrophobic Interaction ◽  
Self Assembly ◽  
Small Angle Neutron Scattering ◽  
Mass Fraction ◽  
Temperature Sensitive ◽  
Vesicular Structure ◽  
Wide Range ◽  
Scattering Measurements ◽  
Potential Applications

A self-assembled unilamellar vesicle, which can be used as a drug delivery system, was easily and simply fabricated using a blended system of Pluronic block copolymers. Controlling the hydrophilic mass fraction of block copolymers (by blending the block copolymer with a different hydrophilic mass fraction) and temperature (i.e., the hydrophobic interaction is controlled), a vesicular structure was formed. Small angle neutron scattering measurements showed that the vesicular structure had diameters of empty cores from 13.6 nm to 79.6 nm, and thicknesses of the bilayers from 2.2 nm to 8.7 nm when the hydrophobic interaction was changed. Therefore, considering that the temperature of the vesicle formation is controllable by the concentration of the blended block copolymers, it is possible for them to be applied in a wide range of potential applications, for example, as nanoreactors and nanovehicles.

scholarly journals Experimental and computational investigation of temperature effects on soot mechanisms

2014 ◽  
Vol 79 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Xiaojie Bi ◽  
Maoyu Xiao ◽  
Xinqi Qiao ◽  
Chia-Fon Lee ◽  
Liu Yu
Keyword(s):  
Ambient Temperature ◽  
Soot Formation ◽  
Oxidation Mechanism ◽  
Soot Oxidation ◽  
Ambient Temperatures ◽  
Operation Conditions ◽  
Constant Volume Chamber ◽  
Soot Mass ◽  
Soot Measurement ◽  
Soot Model

Effects of initial ambient temperatures on combustion and soot emission characteristics of diesel fuel were investigated through experiment conducted in optical constant volume chamber and simulation using phenomenological soot model. There are four difference initial ambient temperatures adopted in our research: 1000 K, 900 K, 800 K and 700 K. In order to obtain a better prediction of soot behavior, phenomenological soot model was revised to take into account the soot oxidation feedback on soot number density and good agreement was observed in the comparison of soot measurement and prediction. Results indicated that ignition delay prolonged with the decrease of initial ambient temperature. The heat release rate demonstrated the transition from mixing controlled combustion at high ambient temperature to premixed combustion mode at low ambient temperature. At lower ambient temperature, soot formation and oxidation mechanism were both suppressed. But finally soot mass concentration reduced with decreasing initial ambient temperature. Although the drop in ambient temperature did not cool the mean in-cylinder temperature during the combustion, it did shrink the total area of local high equivalence ratio, in which soot usually generated fast. At 700 K initial ambient temperature, soot emissions were almost negligible, which indicates that sootless combustion might be achieved at super low initial temperature operation conditions.

A Simplified Method to Evaluate the Impact of Component Design on Engine Performance

2007 ◽  
Author(s):  
Francesco Montella ◽  
J. P. van Buijtenen
Keyword(s):  
Design Process ◽  
Engine Performance ◽  
Simulation Software ◽  
Fast Method ◽  
Engine Simulation ◽  
Engine Model ◽  
Component Design ◽  
Wide Range ◽  
Engine Component ◽  
The Impact

This paper presents a simplified and fast method to evaluate the impact of a single engine component design on the overall performance. It consists of three steps. In the first step, an engine system model is developed using available data on existing engines. Alongside the cycle reference point, a sweep of operating points within the flight envelop is simulated. The engine model is tuned to match a wide range of conditions. In the second step, the module that contains the engine component of interest is analyzed. Different correlations between the component design and the module efficiency are investigated. In the third step, the deviations in efficiency related to different component configurations are implemented in the engine baseline model. Eventually, the effects on the performances are evaluated. The procedure is demonstrated for the case of a two-spool turbofan. The effects of tip leakage in the low pressure turbine on the overall engine performance are analyzed. In today’s collaborative engine development programs, the OEMs facilitate the design process by using advanced simulation software, in-house available technical correlations and experience. Suppliers of parts have a limited influence on the design of the components they are responsible for. This can be rectified by the proposed methodology and give subcontractors a deeper insight into the design process. It is based on commercially available PC engine simulation tools and provides a general understanding of the relations between component design and engine performance. These relations may also take into account of aspects like production technology and materials in component optimization.

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