Large Eddy Simulation of Evaporating Spray with a Stochastic Breakup Model

2013 ◽  
Author(s):  
Abolfazl Irannejad ◽  
Farhad Jaberi
Keyword(s):  
Large Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Evaporating Spray ◽  
Breakup Model

scholarly journals Large-Eddy Simulation of ECN Spray A: Sensitivity Study on Modeling Assumptions

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3360
Author(s):  
Mahmoud Gadalla ◽  
Jeevananthan Kannan ◽  
Bulut Tekgül ◽  
Shervin Karimkashi ◽  
Ossi Kaario ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Sensitivity Study ◽  
Droplet Breakup ◽  
Injection Volume ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Subgrid Scales ◽  
Secondary Breakup ◽  
Breakup Model ◽  
Model Approach

In this study, various mixing and evaporation modeling assumptions typically considered for large-eddy simulation (LES) of the well-established Engine Combustion Network (ECN) Spray A are explored. A coupling between LES and Lagrangian particle tracking (LPT) is employed to simulate liquid n-dodecane spray injection into hot inert gaseous environment, wherein Lagrangian droplets are introduced from a small cylindrical injection volume while larger length scales within the nozzle diameter are resolved. This LES/LPT approach involves various modeling assumptions concerning the unresolved near-nozzle region, droplet breakup, and LES subgrid scales (SGS) in which their impact on common spray metrics is usually left unexplored despite frequent utilization. Here, multi-parametric analysis is performed on the effects of (i) cylindrical injection volume dimensions, (ii) secondary breakup model, particularly Kelvin–Helmholtz Rayleigh–Taylor (KHRT) against a no-breakup model approach, and (iii) LES SGS models, particularly Smagorinsky and one-equation models against implicit LES. The analysis indicates the following findings: (i) global spray characteristics are sensitive to radial dimension of the cylindrical injection volume, (ii) the no-breakup model approach performs equally well, in terms of spray penetration and mixture formation, compared with KHRT, and (iii) the no-breakup model is generally insensitive to the chosen SGS model for the utilized grid resolution.

Effects of Fuel Physical Properties and Breakup Model Constants on Large-Eddy Simulation of Diesel Sprays

2015 ◽  
Author(s):  
Chi-Wei Tsang ◽  
Christopher J. Rutland
Keyword(s):  
Molecular Weight ◽  
Large Eddy Simulation ◽  
Physical Properties ◽  
Time Constant ◽  
Momentum Exchange ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Momentum Fluxes ◽  
Length Constant ◽  
Breakup Model

The Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup model is a commonly used model in predicting primary and secondary atomization and breakup processes in Lagrangian-Eulerian Diesel spray simulations. Droplet sizes predicted by this model are dependent on several parameters. The parameters include fuel physical properties, such as density, viscosity, and surface tension, and a number of adjustable model constants, such as KH and RT time constants, KH and RT size constants, and the breakup length constant. The purpose of this study is to investigate the effects of these parameters on predicting spray motions using large-eddy simulation with the dynamic structure sub-grid stress model. The code used in this study is OpenFOAM. This study has three major parts. Firstly, effects of the model constants on the prediction of momentum exchange process were examined by comparing liquid and gas momentum fluxes. Drag Forces exerted on liquid spray by gas phase can be determined from the slopes of gas and liquid momentum fluxes plotted against axial distance. We found that the prediction of momentum exchange between gas and liquid is most sensitive to the KH time constant, B1, among the other model constants. Secondly, effects of fuel physical properties were investigated by using four different fuels in the simulations of non-vaporizing and vaporizing sprays. The four fuels used were n-dodecane, F76 fuel, n-hexadecane, and methyl tetradecanoate. The F76 fuel is a multi-component fuel containing twenty-one hydrocarbons. Global spray quantities such as liquid and vapor penetrations, Sauter mean diameter, total liquid mass, number of parcels, and breakup model quantities such as Ohnesorge number and KH wave speed were compared. The key finding is that not all of these quantities monotonically increase or decrease with fuel molecular weight. Lastly, effects of fuel physical properties on sensitivities of the breakup model constants were studied. We compared liquid penetration and vapor penetration for each fuel using different values of the model constants. We found that the prediction of vapor penetrations is more sensitive to the KH time constant B1 when a fuel with lighter molecular weight was used, and the prediction of liquid penetrations is sensitive to the breakup length constant, Cb, in all of the four fuels. The computational investigations in this study reveal some limitations of the current spray breakup model, and motivate us to develop more advanced models to overcome these limitations.

Large-eddy simulation of evaporating spray in a coaxial combustor

2009 ◽  
Vol 32 (2) ◽  
pp. 2247-2256 ◽  
Author(s):  
Sourabh V. Apte ◽  
Krishnan Mahesh ◽  
Parviz Moin
Keyword(s):  
Large Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Evaporating Spray

scholarly journals Development of Breakup Model for Large Eddy Simulation of Diesel Spray

2013 ◽  
Vol 7 (12) ◽  
Author(s):  
Tatsunori Fujii ◽  
Koji Kitaguchi ◽  
Soichi Hatori ◽  
Tsukasa Hori ◽  
Jiro Senda
Keyword(s):  
Large Eddy Simulation ◽  
Diesel Spray ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Breakup Model

Effect of breakup model on large-eddy simulation of diesel spray evolution under high back pressures

2014 ◽  
Vol 15 (5) ◽  
pp. 522-538 ◽  
Author(s):  
Koji Kitaguchi ◽  
Tatsunori Fujii ◽  
Soichi Hatori ◽  
Tsukasa Hori ◽  
Jiro Senda
Keyword(s):  
Large Eddy Simulation ◽  
Diesel Spray ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Breakup Model
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