A Novel CFD Approach for an Improved Prediction of Particulate Emissions in GDI Engines by Considering the Spray-Cooling on the Piston

Köpple, Fabian; Jochmann, Paul; Hettinger, Alexander; Kufferath, Andreas; Bargende, Michael

doi:10.4271/2015-01-0385

Cited by 10 publications

(8 citation statements)

References 13 publications

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“…In order to understand the mechanism governing PM formation and oxidation as well as the final exhaust-out emissions in GDI engines, optical techniques (Sementa et al, 2012;Stojkovic et al, 2005) and computational fluid dynamics (Bonatesta et al, 2014;Jiao et al, 2015;Köpple et al, 2015) have been used. It is agreed in the literature that the sources of PM formation are i) the presence of rich in fuel pockets during the combustion even in homogeneous mixtures ii) wall fuel-film formation due to fuel impingement and thus, pool fire and iii) carbonization of non-combusted fuel droplets (Bonatesta et al, 2014;Drake et al, 2003;Köpple et al, 2015;Song et al, 2015). The presence of pool fires is unavoidable in the wall-guided GDI engines (Song et al, 2015) and for gasoline engines the lack of oxygen can limit the oxidation of PM (Winklhofer et al, 2011).…”

Section: Number Of Primary Particles and Radius Of Gyrationmentioning

confidence: 99%

Impact of exhaust gas fuel reforming and exhaust gas recirculation on particulate matter morphology in Gasoline Direct Injection Engine

Bogarra

Herreros

Tsolakis

et al. 2017

Journal of Aerosol Science

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Section: Number Of Primary Particles and Radius Of Gyrationmentioning

confidence: 99%

Impact of exhaust gas fuel reforming and exhaust gas recirculation on particulate matter morphology in Gasoline Direct Injection Engine

Bogarra

Herreros

Tsolakis

et al. 2017

Journal of Aerosol Science

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“…Several influencing factors on particle emissions have been investigated in the research community. Ko¨pple et al considered a new approach to predict PN emissions via computational fluid dynamics (CFD) simulation by considering the spray cooling on the piston [5]. The first measurements were published by Ko¨pple et al in 2013 [3].…”

Section: Literature Results On Wall Films and Diffusive Combustionmentioning

confidence: 99%

“…Theoretically fuel-rich zones should not exist for the homogeneous, stoichiometric operation of a GDI engine. According to earlier investigations, it is known that spray–wall interaction is one of the main causes of soot formation in GDI engines [2–6].…”

Section: Introductionmentioning

confidence: 99%

Effect of implementing large-scale charge motion, reducing hydraulic flow of the injector and increasing injection pressure on particle emissions of a GDI engine at WOT and boosted operation

Bertsch

Weidenlener

Dörnhöfer

et al. 2016

International Journal of Engine Research

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Gasoline direct injection (GDI) shows advantages compared with port fuel injection (PFI) regarding efficiency and specific power. Due to stricter regulations for fuel consumption (via the regulation of carbon dioxide), GDI engines are becoming increasingly favourable compared with PFI engines. Therefore the share of GDI engines, especially in combination with turbocharging, is increasing in most of the markets with CO 2 regulations. Challenging for GDI engines is the mixture formation process due to the short time between fuel injection and the start of combustion. Thus, the injector needs to provide a fine fuel atomization in a considerably short time. The generated spray pattern thereby interacts with the in-cylinder charge motion to generate an appropriate air-fuel mixture. Because of this challenging mixture formation process, the formation of soot in local fuel-rich areas is possible. Thus GDI engines emit more particles compared with PFI engines and need special attention on the mixture formation process. To understand the reasons for the increased particle number (PN) emissions, a project concerning the cause of particle emissions was started at Institute of Internal Combustion Engines (IFKM) in Karlsruhe in 2011. During the project, different causes for PN emissions were identified. This article discusses the possible reasons for particle emissions under high engine load and low engine speed and shows some possible solutions to reduce the emission of particles. Discussed possible solutions to enhance the mixture formation process are the generation of a large-scale charge motion (tumble and swirl), the reduction of the hydraulic flow of the multi-hole, solenoid-activated injector and an increase of the rail pressure up to 50 MPa. The reduction of the hydraulic flow and the increase of the injection pressure lead to smaller average droplets and thus to a faster evaporation. An implementation of a large-scale charge motion enhances the mixture formation process and leads to a reduction of the emitted PN concentration at high engine load. This is shown for wide open throttle (WOT) as well as for boosted operation. The reduction of the hydraulic flow of the injector by reducing the bore hole diameter at constant number of holes and spray targeting of the injector leads to smaller droplets. By increasing the injection pressure, the injection duration as well as the average droplet size can be reduced and leads to a better homogenization and a further reduced PN concentration.

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“…However, the spreading and receding behavior of real gasoline completely differs from that of isooctane. Figure 1 reveals the sequences of the evaporation process of real gasoline and isooctane wall films over a hot substrate at 80 • C. In order to predict exhaust emissions, the modeling of thin wall films is being intensively pursued [3]. This can only succeed, however, if corresponding experimental data is available for the validation of the simulation models.…”

Section: Introductionmentioning

confidence: 99%

“…They recorded nominal radii of the contact area and evolution of structure over the droplet lifetime under ambient conditions. A large number of studies in the field of droplet spreading and receding processes during evaporation have been summarized in [2,3,9,10] , which also include theoretical considerations of complex processes in the case of sessile droplets. Although a considerable number of articles have attempted to introduce models that describe the behavior of a one-component film layer, a complementary model that can describe the behavior of multi-component mixtures is still missing.…”

Section: Introductionmentioning

confidence: 99%

Analysis of sub-processes of spreading and receding of sessile droplets on a hot substrate

Hajhariri

Schulz

Duill

et al. 2021

ICLASS

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In many technical applications, such as combustion engines, the investigation of the formation of liquid films attracts a lot of attention. The production of soot particles may be directly related to the unburnt liquid fuel film on top of the piston. Understanding the physics behind the simultaneous evaporation and receding of the liquid fuel film is not a simple task. However, this can lead us to model the behavior of film spreading/evaporation and ultimately reduce combustion by-products. To simplify the analysis of sub-processes of fuel film evaporation, studying a sessile droplet is proposed. Due to the complexity of the various phenomena that occur during spreading and receding of a multi-component droplet, conventional models do not take these processes into account. Therefore, we have investigated the time-dependent spreading/receding contact area and simultaneously described the occurring sub-processes that happen for different multi-component liquids on a heated surface. The dependence of temperature and contact area with respect to droplet lifetime are compared. Moreover, using schlieren imaging technique enables to reveals local evaporation during the whole process.

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A Novel CFD Approach for an Improved Prediction of Particulate Emissions in GDI Engines by Considering the Spray-Cooling on the Piston

Cited by 10 publications

References 13 publications

Impact of exhaust gas fuel reforming and exhaust gas recirculation on particulate matter morphology in Gasoline Direct Injection Engine

Impact of exhaust gas fuel reforming and exhaust gas recirculation on particulate matter morphology in Gasoline Direct Injection Engine

Effect of implementing large-scale charge motion, reducing hydraulic flow of the injector and increasing injection pressure on particle emissions of a GDI engine at WOT and boosted operation

Analysis of sub-processes of spreading and receding of sessile droplets on a hot substrate

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