Effects of Turbulence on the secondary breakup of droplets in diesel fuel sprays

Khaleghi, Hassan; Sani, Hossein Farani; Ahmadi, Masoud; Mohammadzadeh, Faezeh

doi:10.1177/0954407020958581

Cited by 9 publications

(3 citation statements)

References 28 publications

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“…Therefore, it results in an inaccurate prediction of the breakup phenomenon. Khaleghi et al (2021) investigated the influence of turbulence on the secondary breakup using a modified model and found good agreement between simulation results with the experimental results. They concluded that turbulence resulted in an earlier breakup, higher evaporation rate, and lower penetration.…”

Section: Overview Of Research Studiesmentioning

confidence: 75%

Spray Breakup Modelling for Internal Combustion Engines

Sonawane

Ágarwal

2021

Energy, Environment, and Sustainability

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Rising concerns about emissions have led to a significant tightening of pollution norms for internal combustion (IC) engines. High-pressure direct injection (HPDI) technologies have been adopted for most on-road and off-road engines to meet the global demand for clean and efficient powertrains. Higher fuel efficiency, superior combustion, and lower pollutant formation are the characteristic features of the HPDI. The introduction of alternative fuels, modified combustion geometry, and novel combustion concepts demand continuous improvement in fuel injection equipment (FIE). The complicated physics of HPDI and its modelling is an active area of research among researchers and engine developers. Fuel-injected in the combustion chamber breaks up into a spray of fine droplets, evaporating, mixing with ambient air, and forming a fuel-air mixture, greatly affecting the engine combustion and emission characteristics. Therefore, it is necessary to study the fuel breakup phenomenon under different engine conditions comprehensively. Detailed understanding of the spray breakup phenomenon is unavailable due to difficulties in optical access, highly dense sprays, complex processes, etc. However, recent advances in measurement technologies and computational tools have made it feasible for researchers. This chapter attempts to capture widely used spray breakup models and research studies involving IC engines. Fundamental spray breakup and atomization have been discussed at the beginning of the chapter. Subsequently, the basis and fundamentals of popular spray models have been discussed. Finally, the authors have comprehensively discussed the key contributions in sprays to provide an overall idea about the spray models and their application for IC engine studies. Various spray breakup models such as Blob Model, Linear Instability Sheet Atomization (LISA) Model, Kelvin-Helmholtz (KH) Model, Kelvin-Helmholtz-Aerodynamics Cavitation Turbulence (KH-ACT) Model, RT (Rayleigh-Taylor) Model, Hybrid/Modified Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) Model, Taylor Analogy Breakup (TAB) Model, Enhanced TAB breakup model (ETAB) are discussed briefly in this chapter. Towards the end, a summary of the contents of the chapter is provided, which covers highlights and significant observations.

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Section: Overview Of Research Studiesmentioning

confidence: 75%

Spray Breakup Modelling for Internal Combustion Engines

Sonawane

Ágarwal

2021

Energy, Environment, and Sustainability

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“…Moreover, the droplet size of diesel fuel is larger than that of dual fuel blends. Khaleghi et al [25] investigated the influence of turbulence on secondary droplet disintegration. The turbulent intensity has great influence on the critical We value.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Droplet Behaviors during Spray Breakup Process

et al. 2023

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The variation of droplet parameters during the spray breakup process affects the droplet deposition behavior and accurate application. The aim of this study was to experimentally investigate droplet behaviors along the penetration direction with respect to spray propagation. Particle image analysis (PIA) was applied to obtain the characteristics of droplets at three representative stages (namely, initial, quasi-steady, and end stages) after the start of injection (ASOI). The effects of timing and location on the spray characteristics were thoroughly investigated. First, different morphological changes of spray (droplets, ligaments, and bags) during spray breakup were observed. The experimental results show that droplet size and velocity distinctly increase from upstream to downstream at the initial stage. However, at the quasi-steady and end stages, droplet velocities are similar, and the effects of location are not evident. This indicates that location has a significant effect on droplet behaviors at the initial stage. The mean minimum distance (MD) of droplets first increases considerably and then decreases from upstream to downstream, suggesting that the droplets disperse better at midstream. Moreover, the mean MD at the initial stage exceeds that at the quasi-steady and end stages, denoting that the droplets disperse better with time. Finally, the geometric parameter of droplets and the key stage selection are important for predicting the interaction between the droplets and surfaces.

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“…1,2 Several physical processes involved are nozzle flow such as cavitation, droplet breakup, collision, coalescence, and turbulent dispersion. 3,4 As the injected droplets move further downstream, the primary mechanism of droplet dynamics is the transient interaction between small droplets and large-scale turbulent structures in the dilute region of high-velocity fuel sprays. 5 Thus, the development of different droplet dispersion modeling approaches is required to improve diesel spray simulation in the Eulerian-Lagrangian framework with two-way coupling.…”

Section: Introductionmentioning

confidence: 99%

Effects of different droplet dispersion modeling methods on diesel spray simulation in Eulerian-Lagrangian framework

Yang

Chen

Shao

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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The realistic prediction of spray dynamics and dispersion is one of the main tasks of the combustion simulations in diesel engines. Usually, droplet dispersion modeling accuracy can be improved by the development of turbulence models and stochastic dispersion models. Although droplet dispersion due to turbulence is an important phenomenon in high-velocity fuel sprays, studies on the effect of these models are relatively few. Among these studies, the influence of a common used stochastic dispersion model on spray dynamics is not well understood and the application of hybrid turbulence models to fuel spray simulation in the Eulerian-Lagrangian framework with two-way coupling is still at starting stage. In the present study, a better understanding of the effect of the stochastic model on spray dynamics can be obtained by using a statistical analysis of stochastic dispersion time and velocity of dispersed droplets. In order to assess the ability of the hybrid model to improve the radial spread and the inhomogenous distribution of small droplets produced by a high-pressure injector, a partially averaged Navier-Stokes (PANS) model is implemented in an open-source code OpenFOAM and is compared with an unsteady Reynolds averaged Navier-Stokes (RANS) model and a large eddy simulation (LES) model. The results show the importance of resolving large-scale turbulent structures on droplet dispersion modeling in high-velocity fuel spray simulation. The common stochastic dispersion model used in RANS developed for homogenous, isotropic turbulent flows leads to the non-physical dynamics and distribution of droplets and hence is not applicable to the droplet dispersion which is dominated by the non-stochastic motion of large-scale structures in free shear layers. Using PANS instead of RANS should improve the droplet dispersion modeling accuracy of high-velocity fuel sprays in the development of diesel engines with an advanced injection system.

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Effects of Turbulence on the secondary breakup of droplets in diesel fuel sprays

Cited by 9 publications

References 28 publications

Spray Breakup Modelling for Internal Combustion Engines

Spray Breakup Modelling for Internal Combustion Engines

Characteristics of Droplet Behaviors during Spray Breakup Process

Effects of different droplet dispersion modeling methods on diesel spray simulation in Eulerian-Lagrangian framework

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