Modeling the Effects of Intake Flow Structures on Fuel/Air Mixing in a Direct-injected Spark-Ignition Engine

Han, Zhiyu; Reitz, Rolf D.; Claybaker, Peter J.; Rutland, Christopher J.; Yang, Jia; Anderson, Richard W.

doi:10.4271/961192

Cited by 35 publications

(6 citation statements)

References 18 publications

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“…A strong tumble or swirl motion was found to assist in the wider distribution of liquid fuel and vapour, enhancing the subsequent air–fuel mixing. 16–19…”

Section: Introductionmentioning

confidence: 99%

Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Wang

Zhao

2020

International Journal of Engine Research

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Compared to a four-stroke engine, the two-stroke engine doubles firing frequency and has favourable power-to-weight or power-to-volume ratio as well as engine downsizing to improve the overall powertrain fuel economy. In order to overcome the shortcomings of the conventional cross-flow or loop scavenged two-stroke engines, a two-stroke boosted uniflow scavenged direct injection gasoline engine was designed and its performance was analysed. In this study, three-dimensional computational fluid dynamics simulations were performed to understand the impact of the piston shape design on the scavenging process, in-cylinder flow formation, turbulence level and subsequent fuel/air mixing process in the boosted uniflow scavenged direct injection gasoline engine. Both single injection and split injection strategies were investigated to study the interactions between piston designs and fuel injection strategies to achieve stoichiometric mixture around the spark plug. The results show that the optimised piston with the same opening timing for all scavenge ports could achieve much better scavenging performance than the baseline piston design. In particular, the shallow pistons, that is, Piston #1 and Piston #4, could produce stoichiometric mixture around the spark plug with relatively lower inhomogeneity and higher turbulence kinetic energy around top dead centre when implementing the split injection strategy with start of injection timing at 250/310 °CA.

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“…A strong tumble or swirl motion was found to assist in the wider distribution of liquid fuel and vapour, enhancing the subsequent air–fuel mixing. 16–19…”

Section: Introductionmentioning

confidence: 99%

Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Wang

Zhao

2020

International Journal of Engine Research

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“…Further, in these engines, pumping losses can be avoided through direct injection of fuel without resorting to throttle to vary the load. Also, excess fuel injection during the warm-up period can be avoided in these engines unlike conventional engines [4]. But, in these engines, a homogeneous mixture is required at full load and a stratified one is required at other loads [15e17].…”

Section: Introductionmentioning

confidence: 99%

Effect of piston shape on in-cylinder flows and air–fuel interaction in a direct injection spark ignition engine – A CFD analysis

Harshavardhan

Mallikarjuna

2015

Energy

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“…25 A strong tumble or swirl motion was found to be helpful to spread out both the liquid fuel and vapor distributions, which enhanced the subsequent air–fuel mixing. 26–28 The reverse tumble generated by the upright straight intake ports plays a significant role on the control of the charge stratification and the turbulent kinetic energy (TKE) in a DI gasoline engine. 29 The study on the effect of split injections in a direct injected two-stroke gasoline engine shows that the late injected fuel of the second pulse is affected more by the in-cylinder flow motion and results in a sufficiently rich mixture at the spark plug which ensures a stable initiation of combustion.…”

Section: Introductionmentioning

confidence: 99%

Analysis of mixture formation process in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Wang

Zhao

2017

International Journal of Engine Research

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The two-stroke engine has the great potential for aggressive engine downsizing and downspeeding because of its double firing frequency. For a given torque, it is characterized with a lower mean effective pressure and lower peak in-cylinder pressure than a four-stroke counterpart. In order to explore the potential of two-stroke cycle while avoiding the drawbacks of conventional ported two-stroke engines, a novel two-stroke boosted uniflow scavenged direct injection gasoline engine was proposed and designed. In order to achieve the stable lean-burn combustion in the boosted uniflow scavenged direct injection gasoline engine, the mixture preparation, especially the fuel stratification around the spark plug, should be accurately controlled. As the angled intake scavenge ports produce strong swirl flow motion and complex transfer between the swirl and tumble flows in the two-stroke boosted uniflow scavenged direct injection gasoline engine, the interaction between the in-cylinder flow motions and the direct injection and its impact on the charge preparation in the boosted uniflow scavenged direct injection gasoline engine are investigated in this study by three-dimensional computational fluid dynamics simulations. Both the single injection and split injections are applied and their impact on the mixture formation process is investigated. The start of injection timing and split injection ratio are adjusted accordingly to optimize the charge preparation for each injection strategy. The results show that the strong interaction between the fuel injection and in-cylinder flow motions dominates the mixture preparation in the boosted uniflow scavenged direct injection gasoline engine. Compared to the single injection, the split injection shows less impact on the large-scale flow motions. Good fuel stratification around the spark plug was obtained by the late start of injection timings at 300 °CA/320 °CA with an equal amount in each injection. However, when a higher tumble flow motion is produced by the eight scavenge ports’ design, a better fuel charge stratification can be achieved with the later single injection at start of injection of 320 °CA.

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Modeling the Effects of Intake Flow Structures on Fuel/Air Mixing in a Direct-injected Spark-Ignition Engine

Cited by 35 publications

References 18 publications

Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Effect of piston shape on in-cylinder flows and air–fuel interaction in a direct injection spark ignition engine – A CFD analysis

Analysis of mixture formation process in a two-stroke boosted uniflow scavenged direct injection gasoline engine

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