Progress Towards Diesel Combustion Modeling

Rutland, Christopher J.; Ayoub, Nabil S.; Han, Zhiyu; Hampson, Gregory J.; Kong, Song‐Charng; Mather, D. K.; Musculus, Mark P.; Patterson, Mark; Ricart, Laura M.; Stephenson, Philip; Reitz, Rolf D.

doi:10.4271/952429

Cited by 19 publications

(8 citation statements)

References 36 publications

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“…[2] found the value of the constant in the correlation between the initial turbulent level and the average intake flow velocity through the valves to be equal to k 0 = 0.115. By using this value of k 0 , the turbulent kinetic energy k and its dissipation rate are given by equation (1).…”

Section: Turbulence Modelmentioning

confidence: 99%

“…Thus, the intake flow process should be simulated by using a computation domain which includes the intake port geometry and moving valves in order to set up the initial conditions of spray and combustion event in the engine. Studies performed by Rutland et al [1] showed that the influence of the intake flow on engine combustion modeling is very strong. The intake calculations were made by Rutland et al on a full 3D mesh, whereas combustion calculations were performed on two different 60-degree mesh sectors taken from the same 3D intake flow data set.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the initial flow turbulent conditions at intake valve closure could be determined using correlations derived from the full intake flow simulations. The initial turbulence kinetic energy, k , and its dissipation rate, ε , were defined as [2]: (1) where U is the average intake flow velocity through the valves and A is the average valve open area during intake. The proportionality constants were calculated by using the results of the whole 3D intake flow simulation.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Investigation on the Influence of Physical Parameters on Soot and NOx Engine Emissions

Risi

Donateo

Laforgia

2001

Volume 2: In-Cylinder Processes: Fuel Spray, Flow, Ignition, Combustion, and Emission Formation

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CFD simulations need a certain number of parameters to calibrate both empirical and analytical models. The present investigation aims at identifying the effects of these parameters on the numerical prediction of a modified version of Kiva 3V code, which includes the use of the RNG k-ε model for turbulence, the gas/wall convective heat transfer model proposed by Han, Kelvin-Helmholtz Rayleigh-Taylor spray injection and breakup models. Ignition delay was modeled with the Shell model, whereas the laminar-turbulent characteristic time model was used for combustion. Soot formation and oxidation were calculated using Hiroyasu and Nagle and Strickland-Constable models, respectively. NOx was predicted by using the extended Zel’dovich mechanism. This study was carried out for a common-rail direct injection, small-bore Diesel engine, including the investigation of both numerical and physical parameters. Numerical parameters are intended to be variables related to breakup, turbulence, and combustion models that are adjusted according to grid resolution, engine and injection system geometry, and operating conditions. In particular, the effect of laminar and turbulent time scales, characteristic breakup length and time scales, initial turbulence kinetic energy density, initial swirl velocity profile, on engine emissions was analyzed. The investigated physical parameters were initial swirl ratio, air water content, Schmidt number for mass diffusion. All simulations were performed by changing one of the above parameters at each run and keeping approximately the same pressure and heat release rate curves. Results show that similar pressure vs. crank angle curves can be obtained with different values of these parameters but they lead to very different values of predicted emissions levels. In particular, changes of laminar and turbulent characteristic time resulted in a strong influence on NOx emissions but their effects on soot levels were minor. Mass diffusion characteristics (e.g. Schmidt number) were found to strongly affect both soot and NOx emissions. Spray parameters were found mainly to affect soot formation. Furthermore, NOx and soot emissions showed a dependence on swirl ratio and velocity profile.

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Section: Turbulence Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theoretical Investigation on the Influence of Physical Parameters on Soot and NOx Engine Emissions

Risi

Donateo

Laforgia

2001

Volume 2: In-Cylinder Processes: Fuel Spray, Flow, Ignition, Combustion, and Emission Formation

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“…Both the injection pressure and duration are controlled via ECU to permit precise adjustment for injection rate and total amount of fuel injected during the cycle. The system is applied on two stroke engines [2] as well as in conventional four stroke engines [3], in Diesel engines [4][5][6] alongside with gasoline direct injection "GDI" [7][8][9] albeit it used in Diesel engines earlier. Numerous investigations were carried out to unveil the characteristics of engines when running with such systems.…”

Section: Introductionmentioning

confidence: 99%

Modeling Common Rail Fuel Injection System in Diesel Engines

Wilson¹

2015

ERJ. Engineering Research Journal

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In the present work, a mathematical model is developed to simulate and predict the performance of electronically controlled fuel injection system for diesel engines at different operating conditions. The fuel system employs common rail techniques which characterized by symmetrical fuel injection for all engine cylinders and injection pressure beyond 1 k bar. The resultant spray configuration and the availability of multiple injections each cycle leads to achieve significant improvement in combustion efficiency and emissions. The mathematical model introduced in the present work includes the simulation of control signals from electronic control unit "ECU". The model considered the injection timing and firing order when dealing with multiple injectors. Besides, the model includes mathematical simulation of electromagnet power solenoid valves, kinematics of pump plungers due to cam rotation, dynamics of valves and needles motion and finally the flow of fuel through the entire system elements taking into consideration the compressibility effect. The results of the present model are compared with experimental and the available mathematical models to validate the present model. Comparison shows fair agreement. The model shows the great importance of solenoid response in injection timing. The model is proven to be a good tool for exploring the capability of electronically controlled common rail injection system to perform different injection strategies as well as its ability to run with different fuel types. The model can serve also as sub-model in sophisticated CFD codes to simulate realistic combustion process in Diesel engines.

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“…The numerical CFD tools, at their stage of development, can help the engine designers to define the more promising strategies to obtain tailpipe emission control [3][4][5]. Their performances cannot be considered predictive in absolute, but tuning the various model constants for a given engine and on a limited number of test cases, the response of different submodels allows the right scaling of the different arrangements of the combustion system.…”

Section: Introductionmentioning

confidence: 99%

Multi-Dimensional Modeling of Combustion and Pollutants Formation of New Technology Light Duty Diesel Engines

Belardini

Bertoli

1999

Oil & Gas Science and Technology - Rev. IFP

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RŽsumŽ Ñ ModŽlisation multidimensionnelle de la combustion et de la formation des polluants dans les nouveaux moteurs Diesel automobiles Ñ Dans cet article nous prŽsentons les rŽsultats obtenus en utilisant des outils de simulation de la mŽcanique des fluides numŽrique (CFD). Ë partir de rŽsultats expŽrimentaux issus de la caractŽrisation dÕun moteur Diesel common rail, les constantes empiriques de divers mod•les ont ŽtŽ ajustŽes afin dÕobtenir des rŽsultats satisfaisants pour des cas tests reprŽsentatifs. Les principales contraintes des mod•les numŽriques pour obtenir une bonne prŽcision dans les diffŽrents cas dÕŽtudes sont ici analysŽes. Cette analyse numŽrique montre que la CFD permet dŽjˆ, au stade de dŽveloppement atteint, dÕaider les ingŽnieurs ˆ dŽfinir les stratŽgies les plus prometteuses pour ma"triser les Žmissions l ÕŽchappement des moteurs Diesel ˆ injection common rail.

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Progress Towards Diesel Combustion Modeling

Cited by 19 publications

References 36 publications

Theoretical Investigation on the Influence of Physical Parameters on Soot and NOx Engine Emissions

Theoretical Investigation on the Influence of Physical Parameters on Soot and NOx Engine Emissions

Modeling Common Rail Fuel Injection System in Diesel Engines

Multi-Dimensional Modeling of Combustion and Pollutants Formation of New Technology Light Duty Diesel Engines

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