Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

Pulga, Leonardo; Falfari, Stefania; Bianchi, Gian Marco; Ricci, Matteo; Forte, Claudio

doi:10.4271/2020-01-2008

Cited by 4 publications

(2 citation statements)

References 31 publications

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“…It should be noted that the lower is the percentage of the evaporated mass, the higher is the wallfilm thickness, being zero the remaining liquid mass in the spray cloud. All these results can be summarized in the concept of the cooling efficiency, introduced by the authors in [22]. The cooling efficiency, COOLING, was introduced by the authors for assessing the quantity of the 'wasted water', i.e.…”

Section: Thermodynamic Analysismentioning

confidence: 99%

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part I: Non-Reacting Flow Analysis

Falfari¹,

Cazzoli²,

Ricci³

et al. 2021

SAE Technical Paper Series

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Currently engine designers are focusing their attention on the improvement of the engine efficiency, led by the reduction of in-cylinder temperature and the adoption of stoichiometric combustion in the full range of the engine operation map. The most demanding points are those close to full power: water injection is thought to help in fulfilling this goal, thus contributing towards more efficient engines. To perform a rapid optimization of the main parameters involved by the water injection process, it is necessary to have reliable CFD methodologies capable of capturing the most important phenomena. In the present work, a methodological approach based on the CFD simulation of non-reacting flows of S.I. GDI turbocharged engines under water injection operation is pursued using AVL Fire code v. 2020. Port Water Injection (PWI) and Direct Water Injection (DWI) have been tested for the same baseline engine configuration and they have been run at full power condition, at the same rated power engine speed by varying: i) the injection pressure; ii) the injection timing (water injection phasing has significant effect on the water evaporation rate and on its impact on walls); iii) the normalized water injected mass on the stoichiometric fuel mass. The main results have been checked in terms of evaporation rate, cooling temperature, and efficiency, also considering the mixture quality and the fluid-dynamics aspects, in particular the possible degeneration of the turbulence level during the water injection process. The main aim of these simulations is to maximize water injection benefits and minimize possible disadvantage, such as primarily oil dilution and incomplete water evaporation to reduce water tank volume and refilling frequency. Water injection has demonstrated to allow to adopt higher compression ratio with limited penalties on performance. Therefore, for pursuing the target of improving the engine efficiency over the whole engine map and maintaining good performance level, the geometric compression ratio of the baseline engine has been increased. The adopted CFD methodology has shown to be able to capture the thermodynamic effects of water injection.

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Section: Thermodynamic Analysismentioning

confidence: 99%

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part I: Non-Reacting Flow Analysis

Falfari¹,

Cazzoli²,

Ricci³

et al. 2021

SAE Technical Paper Series

View full text Add to dashboard Cite

show abstract

“…GDI engines, starting from the main properties of the water [15,16]. The anti-knock attitude of the water, related to its high cooling effect, was experimentally and numerically assessed [17,18,19,20,21,22], also highlighting the consequent flame slowdown [23].…”

Section: Literature Surveymentioning

confidence: 99%

Thermal Efficiency Enhancement for Future Rightsized Boosted GDI Engines - Effectiveness of the Operation Point Strategies Depending on the Engine Type

Falfari

Bianchi

Cazzoli

et al. 2021

SAE Technical Paper Series

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Internal combustion engines are the primary transportation mover for today society and they will likely continue to be for decades to come. Hybridization is the most common solution to reduce the petrol-fuels consumption and to respect the new raw emission limits. The gasoline engines designed for running together with an electric motor need to have a very high thermal efficiency because they must work at high loads, where engine thermal efficiency is close to the maximum one. Therefore, the technical solutions bringing to thermal efficiency enhancement were adopted on HVs (Hybrid Vehicles) prior to conventional vehicles. In these days, these solutions are going to be adopted on conventional vehicles too.The purpose of this work was to trace development guidelines useful for engine designers, based on the target power and focused on the maximization of the engine thermal efficiency, following the engine rightsizing concept. The originality of the present work stands in the comparison of the effectiveness of the most common strategies adopted today between two types of engine. The chosen engines for this study were modern boosted GDI engines, in line with the current automotive market, designed by CAD at the University of Bologna. 3D CFD computations of nonreacting flows were carried out by means Fire Code 2020 by AVL. The paper aimed to numerically investigate the rightsizing concept depending on the target level of power: two levels of power were chosen, 290 kW and 120 kW respectively, typical the former one of a high-power engine, the last one of an engine more devoted to efficiency purposes. The two engine bores were selected based on the common automotive solutions depending on the target power: 84 mm for the high-power engine, 75 mm for the other engine. Once fixed the bore value and pursuing the maximization of the thermal efficiency, a study on the possible geometries was performed, searching for the best stroke-to-bore ratio S/B: the long stroke engine design finds its limit in the maximum average piston speed, depending on the engine regime at maximum power. Then, the study was moved to the compression ratio increase and the adoption of over-expanded cycles, both aimed to increase the thermal efficiency. For solving the knocking issues arising from the adoption of increased compression ratio, the water injection strategy was analyzed too. Finally, some considerations were deduced on the effectiveness in applying the over-expanded cycles to the two different types of engine: the critical point to be solved is if the applicability and thus the effectiveness of the over-expanded cycles depend on the engine type.

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Experimental and chemical-kinetic evaluation of a heavy-duty methanol PFI engine with direct water injection

Lius,

Sjöberg,

Cronhjort

et al. 2024

Fuel

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Advanced Combustion Modelling of High BMEP Engines under Water Injection Conditions with Chemical Correlations Generated with Detailed Kinetics and Machine Learning Algorithms

Cited by 4 publications

References 31 publications

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part I: Non-Reacting Flow Analysis

PWI and DWI Systems in Modern GDI Engines: Optimization and Comparison Part I: Non-Reacting Flow Analysis

Thermal Efficiency Enhancement for Future Rightsized Boosted GDI Engines - Effectiveness of the Operation Point Strategies Depending on the Engine Type

Experimental and chemical-kinetic evaluation of a heavy-duty methanol PFI engine with direct water injection

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