3D CFD Analysis of the Influence of Some Geometrical Engine Parameters on Small PFI Engine Performances – the Effects on the Tumble Motion and the Mean Turbulent Intensity Distribution

Falfari, Stefania; Brusiani, Federico; Pelloni, P.

doi:10.1016/j.egypro.2014.01.075

Cited by 17 publications

(5 citation statements)

References 21 publications

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“…Figure 9 shows the great reducing effect of CR on η i at constant λ and the main reasons are as followed. On the one hand, the operating conditions with higher CR in Figure 9 exhibit higher T c (Table 4) and this contributes to increase the heat transfer; on the other hand, the higher CR amplifies the tumble motion breakdown, as reported by Falfari et al [28]. This phenomenon promotes the in-cylinder turbulence that increases the convective coefficient and, in turn, the heat exchanges.…”

Section: Resultsmentioning

confidence: 50%

“…In particular, an increase in λ mitigates the effect of CR slightly reducing the heat exchanges and increasing the internal efficiency. 4) and this contributes to increase the heat transfer; on the other hand, the higher CR amplifies the tumble motion breakdown, as reported by Falfari et al [28]. This phenomenon promotes the in-cylinder turbulence that increases the convective coefficient and, in turn, the heat exchanges.…”

Section: Resultsmentioning

confidence: 67%

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Analysis of the Combustion Process in a Hydrogen-Fueled CFR Engine

2023

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Green hydrogen, produced using renewable energy, is nowadays one of the most promising alternatives to fossil fuels for reducing pollutant emissions and in turn global warming. In particular, the use of hydrogen as fuel for internal combustion engines has been widely analyzed over the past few years. In this paper, the authors show the results of some experimental tests performed on a hydrogen-fueled CFR (Cooperative Fuel Research) engine, with particular reference to the combustion. Both the air/fuel (A/F) ratio and the engine compression ratio (CR) were varied in order to evaluate the influence of the two parameters on the combustion process. The combustion duration was divided in two parts: the flame front development (characterized by laminar flame speed) and the rapid combustion phase (characterized by turbulent flame speed). The results of the hydrogen-fueled engine have been compared with results obtained with gasoline in a reference operating condition. The increase in engine CR reduces the combustion duration whereas the opposite effect is observed with an increase in the A/F ratio. It is interesting to observe how the two parameters, CR and A/F ratio, have a different influence on the laminar and turbulent combustion phases. The influence of both A/F ratio and engine CR on heat transfer to the combustion chamber wall was also evaluated and compared with the gasoline operation. The heat transfer resulting from hydrogen combustion was found to be higher than the heat transfer resulting from gasoline combustion, and this is probably due to the different quenching distance of the two fuels.

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Section: Resultsmentioning

confidence: 50%

Section: Resultsmentioning

confidence: 67%

Analysis of the Combustion Process in a Hydrogen-Fueled CFR Engine

2023

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“…The results were displayed in a graph showing a distinctly different flow distribution than the one obtained in the poppet valve model (Figure 12). As can be found in [17], the flow field in the cylinder can be examined as a rotating solid body which centre of rotation is the stationary mass in the centre of the vortex. Using this reasoning, the rotation speed of the vortices can be determined according to the well-known calculation:…”

Section: Calculation Resultsmentioning

confidence: 99%

A Complex Comparatrive Study of Two Dissimilar Engine Valve Constructions, for the In-Cylinder Flow Behaviour of a High Speed, IC Engine

Kovács,

Bolló,

Szabó

2024

ACTA POLYTECH HUNG

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In our research we investigated the possibility of offering a viable alternative for internal combustion engines' poppet valves. After examining in-cylinder flow characterization methods, we derived a computer model of the base concept and a special swinging valve arrangement. The flow characterization of both arrangements has been completed using numerical fluid dynamics software. To minimize numerical errors different mesh scenarios were investigated and evaluated. From our research activity a clear picture has been drawn on the qualities of the proposed system. The swinging valve arrangement improves the efficiency of the gas exchange process. Also, the flow during the intake process is more structured and has less local vorticity. The results have also shown a very favourable charge movement pattern that is ideal for GDI engines. All of these findings produce an appropriate platform for a stratified charging, extra lean burning engine concept. The construction concept lends itself to be flawlessly integrated in a throttle-less engine control environment as well. With these qualities the new valve arrangement may be the ideal solution to produce fuel efficient, high specific output engines, for those transportation systems that will still need to rely on fossil fuels in the future.

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“…Authors in [3] focused on the effect of the joint use of the tumble and the squish flows in promoting the incylinder turbulence for fast combustion purposes. The squish velocity to the tumble velocity ratio at TDC was used to evaluate the effectiveness of the joint use of the tumble and the squish flow.…”

Section: Literature Summary On the Tumble Motionmentioning

confidence: 99%

3D CFD Analysis of the Influence of Some Geometrical Engine Parameters on Small PFI Engine Performances - The Effects on Tumble Motion and Mean Turbulent Intensity Distribution

Falfari¹,

Bianchi²,

Nuti³

2012

SAE Technical Paper Series

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In scooter/motorbike engines coherent and stable tumble motion generation is still considered an effective mean in order to both reduce engine emissions and promote higher levels of combustion efficiency. The promotion of a stable and coherent tumble structure is largely believed in literature to enhance in-cylinder turbulence accelerating combustion process. In small PFI engine layout and weight constraints limit the adoption of more advanced concepts. In previous technical papers the authors demonstrated the influence of head shape and squish area on tumble vortex formation, development, breakdown and on final value of turbulence close to spark plug for small PFI engines. The main result of the this research was that the combustion chamber having the less squish area resulted to have the highest level of turbulence close to spark plug at ignition time. The geometry under analysis in the current paper is a 3-valves pent-roof motorcycle engine. 3D CFD simulations were ran at 6500 rpm with AVL FIRE code. The chosen engine geometry was the geometry found to be the best setup in terms of turbulence and combustion performances in the previous paper. In the present paper the head shape and the squish area were kept constant and the following engine parameters were varied: the intake duct angle (the angle of the intake duct entering the head was reduced of 6%, i.e. it was more directed toward the exhaust side of the chamber), the piston shape, and finally the compression ratio (it was reduced of 9%). The main goal of the current analysis is to understand which of these parameters is predominant in accelerating combustion for directing engine design toward the best setup .

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3D CFD Analysis of the Influence of Some Geometrical Engine Parameters on Small PFI Engine Performances – the Effects on the Tumble Motion and the Mean Turbulent Intensity Distribution

Cited by 17 publications

References 21 publications

Analysis of the Combustion Process in a Hydrogen-Fueled CFR Engine

Analysis of the Combustion Process in a Hydrogen-Fueled CFR Engine

A Complex Comparatrive Study of Two Dissimilar Engine Valve Constructions, for the In-Cylinder Flow Behaviour of a High Speed, IC Engine

3D CFD Analysis of the Influence of Some Geometrical Engine Parameters on Small PFI Engine Performances - The Effects on Tumble Motion and Mean Turbulent Intensity Distribution

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