Numerical Study of the Scavenging Process in a Large Two-Stroke Marine Engine Using URANS and LES Turbulence Models

Nemati, Arash; Ong, Jiun Cai; Jensen, Michael Vincent; Pang, Kar Mun; Mayer, Stefan; Walther, Jens Honoré

doi:10.4271/2020-01-2012

Cited by 10 publications

(10 citation statements)

References 19 publications

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“…Nemati et al applied URANS and LES on the scavenging process of a large 2-stroke diesel engine and compared their results with PIV data. Although they found a good agreement with the measurements for both solutions, too, they stated a better prediction of the tangential velocity for LES [16]. Very similar results were found for an uniflow-scavenged cylinder in [17] and for an optical engine in [18].…”

Section: Basic Challenges Of Turbulent In-cylinder Flowsupporting

confidence: 58%

Towards a Predictive Simulation of Turbulent Combustion?—An Assessment for Large Internal Combustion Engines

Lauer

Frühhaber

2020

Energies

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Frequently the question arises in what sense numerical simulation can be considered predictive if prior model tuning with test results is necessary. In this paper a summary of the present Computational Fluid Dynamics (CFD) simulation methods for in-cylinder modelling is presented with a focus on combustion processes relevant for large engines. The current discussion about the sustainability of internal combustion engines will have a strong impact on applying advanced CFD methods in industrial processes. It is therefore included in the assessment. Simplifications and assumptions of turbulence, spray, and combustion models, as well as uncertainties of model boundary conditions, are discussed and the future potential of an advanced approach like Large Eddy Simulation (LES) is evaluated. It follows that a high amount of expertise and a careful evaluation of the numerical results will remain necessary in the future to apply the best-suited models for a given combustion process. New chemical mechanisms will have to be developed in order to represent prospective fuels like hydrogen or OME. Multi-injection or dual fuel combustion will further pose high requirements to the numerical methods. Therefore, the further development and validation of advanced mixture, combustion and emission models will remain important. Close cooperation between academia, code suppliers and engine manufacturers could promote the necessary progress.

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Section: Basic Challenges Of Turbulent In-cylinder Flowsupporting

confidence: 58%

Towards a Predictive Simulation of Turbulent Combustion?—An Assessment for Large Internal Combustion Engines

Lauer

Frühhaber

2020

Energies

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“…From the turbochargers, the air is led via the charging air pipe, through air coolers and scavenge air receiver to ports of the cylinder liners [31]. The scavenging process is responsible for delivering fresh air to the combustion chamber and removing combustion gases in the cylinder [32]. The scavenging process affects the air pollution and its operation is strictly controlled and regulated [33]; it improves the combustion efficiency due to a better air/gas exchange [34].…”

Section: Ati-2023mentioning

confidence: 99%

Preliminary experimental data analysis for Digital Twin development of a large bore Dual-Fuel engine

Mondo,

Pivetta,

Fratti

et al. 2023

J. Phys.: Conf. Ser.

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In recent years, digital models, and in particular Digital Twins (DTs), have seen a growing interest due to their ability to provide support in the development of more efficient systems and processes. This study presents the preliminary steps taken to develop a DT model for a marine Large Bore Dual-Fuel engine manufactured by Wärtsilä. The correlation between dependend and independent data set variables is presented in order to map the engine behaviour and validate the DT model before becoming operational. The analyses are conducted using the engine in gas mode, operating at 85% of Load (at the nominal speed of 600rpm). This operating point represents the typical target design for constant speed applications. The engine efficiency, emissions and combustion chamber parameters are investigated by varying the air-fuel mixture pressure, timing and duration parameters. Sensitivity analysis presents a tight relation between Nitrogen Oxides and Hydrocarbons (HC) emissions by varying the Scavenging Air Pressure. The HC emission function around the nominal value of the Pilot Fuel Injection Duration reverse its trend, while In Cylinder-Pressure and Combustion Duration functions presents opposite gradients. By advancing the Pilot Fuel Injection timing is shown an increase in Engine Efficiency respect to others input parameters.

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“…Through 1D model simulations on a diesel engine with a cylinder bore of 500 mm, the results indicated that this technology can improve the thermal efficiency, reduce the fuel consumption by 4.3 g/(kW•h), and benefit the design and cost-efficiency of SCR systems. Computational Fluid Dynamics (CFD) has been extensively employed to analyze the scavenging and combustion processes of low-speed two-stroke diesel engines [24][25][26][27]. However, few literature works have utilized the CFD method to assess the effects of the VPT technology on the operational procedures of marine low-speed two-stroke engines.…”

Section: Model Description and Validationmentioning

confidence: 99%

“…Computational Fluid Dynamics (CFD) has been extensively employed to analyze the scavenging and combustion processes of low-speed two-stroke diesel engines [24][25][26][27]. However, few literature works have utilized the CFD method to assess the effects of the VPT technology on the operational procedures of marine low-speed two-stroke engines.…”

Section: Introductionmentioning

confidence: 99%

Numerical Research on Effects of Variable Port Timing on Performance of Marine Low-Speed Two-Stroke Engine

Zhang,

Long,

Xiao

et al. 2023

Processes

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Enhancing the effective expansion ratio to further improve the fuel consumption, this study implemented a kind of Variable Port Timing (VPT) by designing a vertically moving sleeve on the outside of the scavenging port of a low-speed two-stroke diesel engine with a 340 mm bore. A 3D Computational Fluid Dynamics (CFD) model was constructed and calibrated to investigate the influence of the VPT strategy on the engine performance and the internal gas exchange process. The results indicated that the VPT can reduce the negative work from the compression stroke and increase the expansion work from the expansion stroke, which effectively enhances the fuel economy. However, the reduction in the mass flow rate would lead to the severe deterioration of the turbocharging system’s performance. The related matching analysis between the sleeve and the scavenging ports revealed that the sleeve velocity had a minimal influence on the scavenging flow rate, while increasing the height of the scavenging port can restore a certain mass flow rate, but will decrease the in-cylinder swirl intensity, deteriorating the combustion in the cylinders. The optimal approach is to raise the position of the scavenging port, achieving a Scavenging Port Closing (SPC) at a 235°CA, which will restore the scavenging flow rate of the original level to 90.7% and improve the indicated fuel consumption by 2.9 g/kWh.

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Numerical Study of the Scavenging Process in a Large Two-Stroke Marine Engine Using URANS and LES Turbulence Models

Cited by 10 publications

References 19 publications

Towards a Predictive Simulation of Turbulent Combustion?—An Assessment for Large Internal Combustion Engines

Towards a Predictive Simulation of Turbulent Combustion?—An Assessment for Large Internal Combustion Engines

Preliminary experimental data analysis for Digital Twin development of a large bore Dual-Fuel engine

Numerical Research on Effects of Variable Port Timing on Performance of Marine Low-Speed Two-Stroke Engine

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