High pressure/high temperature multiphase simulations of dodecane injection to nitrogen: Application on ECN Spray-A

Koukouvinis, Phoevos; Vidal-Roncero, Alvaro; Rodríguez, Carlos; Gavaises, Manolis; Pickett, Lyle M.

doi:10.1016/j.fuel.2020.117871

Cited by 56 publications

(52 citation statements)

References 75 publications

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“…It should be noted that for such small changes in the temperature (ΔT<1 Κ) and pressure (ΔP~1.8 bar) the density of water changes less than 1% and therefore not much difference is expected in the results with the use of constant density; however, this was not known a priori. For the same reason, the rest of fluid properties (surface tension, viscosity, heat capacity and thermal conductivity) are taken constant for the liquid water at the initial temperature of 293.15 K. Preliminary CFD simulations using variable properties for water based on (Lemmon 2013;Wagner and Pruß 2002) and the tabulated method of et al 2020) have shown that the droplet deformation in both axes changes less than 1%, while the leading edge displacement is overestimated by a maximum of 10% at the final stages of the simulation with the constant properties approach, probably due to difference in the fluid viscosity. For the gas phase (air or nitrogen), which has large variations in the pressure and temperature, the heat capacity and thermal conductivity are taken as functions of temperature, using the polynomial functions of (Perry and Green 1999).…”

Section: Equations Of State (Eos) and Rest Of Fluid Propertiesmentioning

confidence: 99%

Numerical Investigation of the Aerodynamic Droplet Breakup at Mach Numbers Greater Than 1

et al. 2021

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Section: Equations Of State (Eos) and Rest Of Fluid Propertiesmentioning

confidence: 99%

Numerical Investigation of the Aerodynamic Droplet Breakup at Mach Numbers Greater Than 1

et al. 2021

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“…More recently, Kaario et al [21] investigated fuel properties effects on the liquid spray formation by replacing n-dodecane in Spray A with other fuels. Seeking a more accurate modeling approach, Koukouvinis et al [41] employed advanced thermophysical closure models to account for capturing complex details of the flow. Following a similar pathway, Matheis and Hickel [42] and Yang et al [43] both accounted for real gas thermodynamics to investigate the co-existence of transcritical effects in the spray, while showing that surface tension effects still persist in the sub-critical regime.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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“…Currently, the data of the ECN represent the most comprehensive database for fuel sprays; relevant predictions have been recently reported; 60 still, effects occurring upon the needle valve closing and the dwelt time between injections have not been studied, while the flow in the single-nozzle considered is a simplification compared to the complex flow distribution in the VCO nozzle studied here. Finally, the recent work 14,39,60,61 provides qualitative validation of a barotropic model against images obtained inside a transparent real-size sac-type nozzle operating at pressures similar to those tested here; this study provides further confidence that the model can capture the coexistence of cavitation vapour and air entrainment during the closing phase of the needle valve and during the dwelt time. As already mentioned, the present manuscript includes further qualitative comparison of the model predictions against the experimental data reported recently by the authors in Gold et al 5 and also the work of Manin et al 53 (2) One of the main assumptions in the described methodology is the mechanical and thermodynamic equilibrium between the liquid, vapour and air.…”

Section: Limitations Link To Previous Work and Present Contributionmentioning

confidence: 99%

Numerical simulation of fuel dribbling and nozzle wall wetting

Gavaises

Murali-Girija

Rodríguez

et al. 2021

International Journal of Engine Research

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The present work describes a numerical methodology and its experimental validation of the flow development inside and outside of the orifices during a pilot injection, dwelt time and the subsequent start of injection cycle. The compressible Navier-Stokes equations are numerically solved in a six-hole injector imposing realistic conditions of the needle valve movement and considering in addition a time-dependent eccentric motion. The valve motion is simulated using the immersed boundary method; this allows for simulations to be performed at zero lift during the dwelt time between successive injections, where the needle remains closed. Moreover, the numerical model utilises a fully compressible two-phase (liquid, vapour) two-component (fuel, air) barotropic model. The air’s motion is simulated with an additional transport equation coupled with the VOF interface capturing method able to resolve the near-nozzle atomisation and the resulting impact of the injected liquid on the oleophilic nozzle wall surfaces. The eccentric needle motion is found to be responsible for the formation of strong swirling flows inside the orifices, which not only contributes to the breakup of the injected liquid jet into ligaments but also to their backwards motion towards the external wall surface of the injector. Model predictions suggest that such nozzle wall wetting phenomena are more pronounced during the closing period of the valve and the re-opening of the nozzle, due to the residual gases trapped inside the nozzle, and which contribute to the poor atomisation of the injected fluid upon re-opening of the needle valve in subsequent injection events.

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High pressure/high temperature multiphase simulations of dodecane injection to nitrogen: Application on ECN Spray-A

Cited by 56 publications

References 75 publications

Numerical Investigation of the Aerodynamic Droplet Breakup at Mach Numbers Greater Than 1

Numerical Investigation of the Aerodynamic Droplet Breakup at Mach Numbers Greater Than 1

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

Numerical simulation of fuel dribbling and nozzle wall wetting

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