Development and Validation of a Primary Breakup Model for Diesel Engine Applications

Som, Sibendu; Ramírez, Anita I.; Kastengren, Alan L.; El-Hannouny, Essam; Longman, Douglas E.; Powell, Christopher F.; Senecal, P. K.

doi:10.4271/2009-01-0838

Cited by 36 publications

(21 citation statements)

References 20 publications

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“…In the present study, the multiphase system is comprised of a liquid phase (1), a vapor phase (2), and noncondensable gases (3). The sum of vapor and noncondensable gases will be referred to with the subscript g. The concept of pseudodensity is used, and the mixture density p is computed with the following equation:…”

Section: Mixture Modelmentioning

confidence: 99%

“…Nozzles can experience fully developed cavitation or even string-type cavitation depending on the sac flow field [1]. Several studies carried out on diesel or gasoline direct injection (GDI) injectors [2][3][4][5][6][7][8] reported that cavitation inside the nozzle orifice generates increased turbulence that contributes greatly to the disintegration of the liquid jet, improving the primary breakup and the subsequent atomization process. Another positive outcome of cavitation, which is usually observed, is a larger spray cone angle.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of Mixture and Multifluid Models for In-Nozzle Cavitation Prediction

Battistoni

Som

Longman

2014

Journal of Engineering for Gas Turbines and Power

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Fuel injectors often feature cavitation because of large pressure gradients, which in some regions lead to extremely low pressures. The main objective of this work is to compare the prediction capabilities of two multiphase flow approaches for modeling cavitation in small nozzles, like those used in high-pressure diesel or gasoline fuel injectors. Numerical results are assessed against quantitative high resolution experimental data collected at Argonne National Laboratory using synchrotron X-ray radiography of a model nozzle. One numerical approach uses a homogeneous mixture model with the volume of fluid (VOF) method, in which phase change is modeled via the homogeneous rela.xation model (HRM). The second approach is based on the multifluid nonhomogeneous model and uses the Rayleigh bubble-dynamics model to account for cavitation. Both models include three components, i.e., liquid, vapor, and air, and the flow is compressible. Quantitatively, the amount of void predicted by the multifluid model is in good agreement with measurements, while the mixture model overpredicts the values. Qualitatively, void regions look similar and compare well with the experimental measurements. Grid converged results have been achieved for the prediction of mass flow rate while gridconvergence for void fraction is still an open point. Simulation results indicate that most of the vapor is produced at the nozzle entrance. In addition, downstream along the centerline, void due to expansion of noncondensable gases has been identifled. The paper also includes a discussion about the effect of turbulent pressure fluctuations on cavitation inception.

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Section: Mixture Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of Mixture and Multifluid Models for In-Nozzle Cavitation Prediction

Battistoni

Som

Longman

2014

Journal of Engineering for Gas Turbines and Power

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“…In support of such methods, Badock et al [7] and later Ganippa et al [8] presented results claiming that nozzle flow characteristics have negligible influence over the spray formation and that momentum is the only controlling variable for mixing. Contrasting these studies, several authors show that the flow inside the nozzle influences the nearnozzle region of the spray in terms of liquid-phase break-up, liquid length, and spray angle [9][10][11][12][13][14][15][16]. Many other studies also evidence the effects of nozzle flow characteristics over the macroscopic spray [3,4,6,11,[17][18][19][20].…”

Section: Introductionmentioning

confidence: 96%

The effect of nozzle geometry over internal flow and spray formation for three different fuels

Payri

Viera

Gopalakrishnan

et al. 2016

Fuel

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h i g h l i g h t sTwo single hole nozzle (cylindrical and convergent) are used. A complete hydraulic characterization is done along with spray visualization. A fast pulsed light source is synchronized to a fast camera working at 160 kHz. The effect of nozzle geometry is analyzed for three different fuels. A large set of experimental data was obtained, which could be used for model validation. a b s t r a c tThe influence of internal nozzle flow characteristics over macroscopic spray development is studied experimentally for two different nozzle geometries and three fuels. The measurements include a complete hydraulic characterization consisting of instantaneous injection rate and spray momentum flux measurements, followed by a high-speed visualization of isothermal liquid spray in combination with cylindrical and conical nozzle configurations. Two of the fuels are pure components-n-heptane and ndodecane-while the third fuel consists of a three-component surrogate to better represent the physical and chemical properties of diesel fuel. The cylindrical nozzle with 8.6% larger diameter, in spite of higher mass flow rate and momentum flux, shows slower spray tip penetration when compared to the conical nozzle. The spreading angle is found to be inversely proportional to the spray tip penetration. The spreading angle is largely influenced by the nozzle geometry and the ambient density. Rail pressure was found to have weak influence on the near-field spreading angle and no influence on the standard deviation of the spreading angle. n-Heptane spray shows slowest penetration rates while n-dodecane and the surrogate fuel mixture show very similar spray behavior for variations in injection pressure and back pressure. However, the surrogate fuel mixture shows higher penetration than n-dodecane when using the conical nozzle and lower penetration than n-dodecane when using cylindrical nozzle.

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“…Using a similar approach, Vishwanathan and Reitz [14] captured the LOL and soot distribution under LTC conditions. Recently, Som and Aggarwal [4] developed an improved primary breakup model Kelvin-Helmholtz Aerodynamic Cavitation Turbulence (KH-ACT), accounting for cavitation and turbulence-induced breakup in addition to aerodynamic breakup [4,15]. The KH-ACT model was coupled with a reduced NHPT model [16] to successfully predict the ignition and flame lift-off behavior for different injection and ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

Simulating Flame Lift-Off Characteristics of Diesel and Biodiesel Fuels Using Detailed Chemical-Kinetic Mechanisms and Large Eddy Simulation Turbulence Model

Som

Longman

Luo

et al. 2012

Journal of Energy Resources Technology

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Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the iifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray deveiopment processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesei and biodiesel fuels, as well as Reynoldsaveraged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame iift-off lengths (LOLs) and ignition delays. Specificaily, rn'o chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the renormalization group (RNG) k-e (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resoitttion, minimum grid sizes of 250 ßm and 125 ^m were obtained for the RANS and LES cases, respectively.Validations of these modeis were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition deiay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-e model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl nine-decenoate, and NHPT, results in better predicted LOLs and ignition deiays. For diesei fuei though, only marginal improvements are obsen'ed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

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Development and Validation of a Primary Breakup Model for Diesel Engine Applications

Cited by 36 publications

References 20 publications

Comparison of Mixture and Multifluid Models for In-Nozzle Cavitation Prediction

Comparison of Mixture and Multifluid Models for In-Nozzle Cavitation Prediction

The effect of nozzle geometry over internal flow and spray formation for three different fuels

Simulating Flame Lift-Off Characteristics of Diesel and Biodiesel Fuels Using Detailed Chemical-Kinetic Mechanisms and Large Eddy Simulation Turbulence Model

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