Research on Model for Diesel Fuel Breakup Based on Cavitation Bubble Collapse Energy

Nishimura, Akihiro; Wakisaka, Tomoyuki

doi:10.5988/jime.40.2_266

Cited by 9 publications

(13 citation statements)

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“…The Rayleigh-Plesset equation describes the growth of a vapour bubble in a liquid: (5) where R B represents the bubble radius, σ represents the surface tension coefficient, and P v represents the vapour pressure. Neglecting the second order terms and the surface tension force yields the simplified expression (6) The rate of change of mass of a single bubble follows as (7) If there are N B bubbles per unit volume, the vapour volume fraction may be expressed as (8) and the total interphase mass transfer rate due to cavitation per unit volume is (9) This model has been derived assuming bubble growth (vaporization). It can be generalized to include condensation as follows:…”

Section: Nozzle Flow Simulationmentioning

confidence: 99%

“…The break-up energy consists of the two following terms: flow induced turbulent kinetic energy E turb [4,8] and cavitation induced turbulent kinetic energy E cav [4,7,9]. Turbulent fluctuations acting on the surface of a jet cause instabilities which lead to break-up.…”

Section: Primary Breakup Modelmentioning

confidence: 99%

“…In the case of primary breakup it is assumed that the main mechanisms that lead to the first breakup of the coherent liquid column into large liquid drops and ligaments can be found inside the injection nozzle. The most cited mechanisms found in the literature are cavitation and turbulence [3,4,6,7,8,9]. These are caused by the large pressure differences (about 2000 bar) and the tiny geometrical dimensions of the nozzle (D = 120 µm), which lead to very high velocities and low static pressures, locally under that of the saturation pressure of diesel.…”

Section: Introductionmentioning

confidence: 99%

“…In the last few years a great effort has been made in an attempt to describe the primary breakup, although not without considerable difficulties due to the lack of experimental studies focusing on this issue [4,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

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Modelling the Influence of the Nozzle Geometry on the Primary Breakup of Diesel Jets

Soriano-Palao

Sommerfeld

Burkhardt

2014

International Journal of Spray and Combustion Dynamics

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In this work, the performance of an enhancement of a well-known, energy based CFD model for the primary breakup of high pressure diesel jets is presented. This new formulation of the model has been developed in order to take into account the different turbulent and cavitating flow conditions experimentally found inside the injection hole (geometric cavitation and "string" cavitation). A detailed spatial and temporal resolution of the cavitating flow in the hole is used by the model to deliver three-dimensional sprays, providing all the starting conditions for the calculation of the secondary breakup of the diesel spray by means of a Lagrangian approach. The characteristic feature of the model is the variable size and velocity distribution of the primary droplets as a function of the available breakup energy. Another main advantage of the model is the direct calculation of the droplet size distribution and spray angle based on the flow properties, so that empirical correlations or measurement data are not needed as input for the calculations. Measurements carried out on real engine nozzles were conducted to validate the simulations of both nozzle flow and spray development.

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Section: Nozzle Flow Simulationmentioning

confidence: 99%

Section: Primary Breakup Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modelling the Influence of the Nozzle Geometry on the Primary Breakup of Diesel Jets

Soriano-Palao

Sommerfeld

Burkhardt

2014

International Journal of Spray and Combustion Dynamics

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“…The major disadvantage of this approach is that it is impossible to use adequate numerical resolution. As the resolution is only possible when the volume fraction of the droplets in a computational cell is less than 10% [51].…”

Section: Eulerian-lagrangian Approachmentioning

confidence: 99%

The Eulerian-Lagrangian Spray Atomization (ELSA) Model of the Jet Atomization in CFD Simulations: Evaluation and Validation

Khuong¹,

Dung²

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Fuel sprays play a major role in order to achieve the required combustion characteristics and pollutant emissions reduction on internal combustion engines, and thus, an accurate prediction of its behavior is required to perform reliable engine combustion and pollutant simulations. A great effort both on experimental and theoretical studies of spray atomization and dispersion has been performed in the latest years. As a result, ComputationalFluid Dynamics (CFD) calculations have become a standard tool not only for spray physics understanding but also for design and optimization of engine spray systems.However, spray modeling in its different uses in the Internal Combustion Engine (ICE) context is still nowadays a challenging task due to the complex interrelated phenomena taking place, some of them still not fully understood.Primary atomization and secondary breakup, droplet collision, coalescence and vaporization, turbulent interactions between phases have to be solved under high Reynolds (so they are turbulent) and Weber numbers conditions due to the high speed (~500 m/s) and small nozzle diameter (~100 µm) imposed by current engine injection systems technologies. Moreover, Taylor numbers cover a wide range, according to the composition of the injected liquid. Those conditions make experimental observations quite challenging and probably insufficient, especially in the very near nozzle region, where primary atomization takes place.Most of the CFD spray models are currently based on the Discrete Droplet Method. The continuous liquid jet is discretized into 'blobs' or 'parcels', which consists in a number of droplets with the same characteristics. ALagrangian method is applied to track the liquid phase parcels, which are subject to breakup according to atomization models mainly based on the linear instability theory proposed by Reitz and later extended by Huh and Gosman for liquid turbulence effects to be considered. This approach has been successfully Abstract ii applied because it is computationally efficient and at the same time is able to provide reasonable agreements with experimental measurements. However, it requires extensive calibration, being this requirement its main drawback, which is caused, on the one hand, by the semi-empirical nature of the liquid phase sub-models, and, on the other hand, for both physical and numerical limitations on the near nozzle dense sprays region description.In According to the previous statements, the first purpose of this PhD thesis has been to perform a validation of the ELSA spray model implemented in the Star-CD code and check it against CMT-Motores Térmicos Institute database. This validation has been made for several engine conditions (evaporative or non-evaporative, cavitating nozzles, cold starting chamber, etc).In all cases, the ELSA model gave accurate and reasonable results, once a proper mesh is made.After this validation, an extensive evaluation of the model in 3D has been made. Probably, the most important result of the thesis is the coupling between a flow co...

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Unraveling the initial flash boiling spray formation at the same superheated index achieved by altering ambient pressure and fuel temperature independently

Atac

Moon

Jeon

2021

International Journal of Heat and Mass Transfer

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Research on Model for Diesel Fuel Breakup Based on Cavitation Bubble Collapse Energy

Cited by 9 publications

References 0 publications

Modelling the Influence of the Nozzle Geometry on the Primary Breakup of Diesel Jets

Modelling the Influence of the Nozzle Geometry on the Primary Breakup of Diesel Jets

The Eulerian-Lagrangian Spray Atomization (ELSA) Model of the Jet Atomization in CFD Simulations: Evaluation and Validation

Unraveling the initial flash boiling spray formation at the same superheated index achieved by altering ambient pressure and fuel temperature independently

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