In-Cylinder Flow Analysis in a Two-Stroke Engine - A Comparison of Different Turbulence Models Using CFD

Addepalli, Srinivasa Krishna; Mallikarjuna, J M; Davinder, Kumar; Babu, Y Ramachandra

doi:10.4271/2013-01-1085

Cited by 27 publications

(3 citation statements)

References 9 publications

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“…In the numerical simulation of the engine, the RNG k – ε two‐equation model coupled with the detailed chemical reaction kinetic mechanism can effectively predict the turbulent flow field changes in the cylinder. Krishna et al 31 used STAR‐CD software to explore the in‐cylinder flow field using different turbulence models on a single‐cylinder two‐stroke engine and compared it with the in‐cylinder velocity field measured by a particle image velocimetry. The results confirm that the RNG k – ε two‐equation model is closer to the experimental measurement results.…”

Section: Methodsmentioning

confidence: 99%

Effect of port water injection on suppressing knock in gasoline direct injection engines

Dai

zheng

Song

2022

Energy Science & Engineering

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The effect of different port water injection (PWI) ratios on the knock in gasoline direct injection engines is explored. First, a simulation study is carried out under knock conditions to explore the time and location of the knock and the chemical mechanism that causes it. Second, water injection amount to 10%, 20%, 30%, and 40% are set to explore the effects of different water injection ratios on knocking. The influence of the different water injection ratios on the chemical mechanism of knocking is evaluated and that of the chemical mechanism on the in‐cylinder temperature and the impact of heat release rate (HRR) is explored. The results show that PWI can effectively reduce the occurrence of spontaneous combustion in the cylinder by reducing the flame propagation speed. On one hand, the changes in the low‐temperature reaction substances CH2O and HRR tend to be consistent and the peaks of CH2O and HRR move back with the increase in water injection. So, different ratios of PWI can affect the flame propagation speed by affecting the generation and consumption of CH2O, OH radicals, and HCO radicals. Also, PWI can significantly reduce the generation of in‐cylinder OH radicals, ultimately suppressing the generation of the high‐temperature stage. In addition, PWI can effectively reduce the mean temperature and mean pressure. Compared to other water injection ratios, a 30% water injection ratio is the most effective at inhibiting knocking. At this time, the knocking intensity is the lowest, and the cycle power reaches its maximum of 1120 J.

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Section: Methodsmentioning

confidence: 99%

Effect of port water injection on suppressing knock in gasoline direct injection engines

Dai

zheng

Song

2022

Energy Science & Engineering

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“…In some cases a characteristic feature of the flow field may provide the most appropriate metric for comparison of velocity fields from PIV, large eddy simulations (LES) or Reynolds averaged Navier Stokes (RANS) modelling. The speed of the flow along the central axis of the intake port (Pera and Angelberger 2011), or the axis of the intake jet (Ameen et al 2017) can be suitable choices, as can the location of vortex centres (Imberdis et al 2007;Yang et al 2014) or spatially averaged tumble ratio (Krishna et al 2013;Koch et al 2014). As well as mean velocities, for LES simulations with many realisations, RMS velocities along selected vertical and horizontal planes have been used to compare the effect of mesh refinement on the simulation of an optical engine (Baumann et al 2014).…”

Section: Methods For Comparing Vector Fieldsmentioning

confidence: 99%

Quantitative metrics for comparison of in-cylinder velocity fields using particle image velocimetry

et al. 2020

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The in-cylinder flow field plays a key role in determining the combustion performance of internal combustion engines (ICEs) and it is critically important to validate numerical simulations of the flow field by comparison to experimental measurements using techniques such as particle image velocimetry (PIV). With the current trend for high-speed diagnostics, methods for quantitative comparison of vector fields are required which can provide robust spatially averaged results, without inspection of individual flow fields. The quality of match between vector fields, when quantified using current metrics such as the relevance index (RI), can be overly sensitive to the alignment of regions of low velocity such as the tumble vortex centre. This work presents complementary metrics, weighted using a function of the local velocity, for robust quantification of the alignment and magnitude differences between vector fields, the weighted relevance index (WRI) and the weighted magnitude index (WMI). These metrics are also normalized and combined in the combined magnitude and relevance index (CMRI). PIV measurements taken up to every 2 crank angle degrees within the tumble plane of a motored, optically accessible ICE are used to demonstrate the motivation for development and the application of the WRI, WMI, and CMRI metrics. The metrics are used to determine the number of cycles required to provide a representative mean flow field and to identify single cycles of interest. Variability of the flow field is quantified using the metrics and shows high variability in the region of the spark plug near typical ignition timings.

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“…For the flow field analysis, conservation equations of mass, momentum and energy are solved. Here, RNG k-ε turbulence model is used [4]. PISO (pressure implicit with splitting of operators) algorithm is used for solving algebraic finite volume equations.…”

Section: Geometrical and Computational Detailsmentioning

confidence: 99%

Effect of Piston Shape on Scavenging in a Two-Stroke Engine - A CFD Analysis

Agrawal

Mallikarjuna

2014

AMM

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This study focuses on effect of piston shape on in-cylinder flows in a conventional loop scavenged two-stroke engine using CFD. Three piston-shapes viz., flat, flat with center-bowl and flat with center-dome are analyzed along with standard piston. The CFD solution has been obtained by using commercial code STAR-CD. First the CFD results are compared with those of experimental values obtained from particle image velocimetry (PIV). For comparison among various piston shapes, various parameters viz., velocity vector plots, tumble ratio (TR), turbulent kinetic energy (TKE) at various crank angles are used. Scavenging and trapping efficiencies are also calculated for each piston configuration. From the results, it is found that flat with center-bowl piston is the best in terms of in-cylinder flow characteristics. It gives higher TR and TKE with very little effect on efficiencies.

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In-Cylinder Flow Analysis in a Two-Stroke Engine - A Comparison of Different Turbulence Models Using CFD

Cited by 27 publications

References 9 publications

Effect of port water injection on suppressing knock in gasoline direct injection engines

Effect of port water injection on suppressing knock in gasoline direct injection engines

Quantitative metrics for comparison of in-cylinder velocity fields using particle image velocimetry

Effect of Piston Shape on Scavenging in a Two-Stroke Engine - A CFD Analysis

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