Begell House Inc.
Atomization and Sprays
AAS
1044-5110
21
1
2011
Dynamic Primary Atomization Characteristics in an Airblast Atomizer, High Pressure Conditions
1-16
10.1615/AtomizSpr.v21.i1.10
Vital Gutierrez
Fernandez
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), Toulouse, France
Gerard
La VERGNE
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), 31055 Toulouse Cedex 4, France
P.
Berthoumieu
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), 31055 Toulouse Cedex 4, France
Airblast
liquid sheet
high pressure testing
atomization mechanisms
oscillation frequency
wave velocity
droplet size
The primary atomization was studied experimentally for several flow configurations, in a planar
airblast atomizer. The liquid sheet injected had a 300μ;m thickness. The employed techniques were
Laser Oscillometry, LDV-PDI, PIV and flow visualization via fast camera. In the liquid flow, the momentum
flux was varied by injecting both water and kerosene JET A1 at several velocities. Conversely, the
airflow momentum flux was modified by adjusting both its velocity and absolute pressure. The latter
parameter reached a value of 11bar. The atomization mechanisms described in the literature at
standard conditions, were observed at the high pressure environments, as long as, the momentum
flux ratio, M, remained constant. Furthermore, a new atomization mechanism was observed for
values of M beyond 20. This regime was referred as membrane break-up due to the predominant
structures observed. The results presented in this manuscript correspond to characteristics related
to the sheets's motion: The global oscillation frequency, the wave velocity gradient in the intact
sheet region and the sauter mean diameter far from the injector lips. Furthermore, these variables
displayed a weak change both in magnitude and behaviour with the changes in atomization
mechanisms. A set of empirical relations are provided to link these characteristics witht the flow
conditions.
Geometric Primary Atomization Characteristics in an Airblast Atomizer, High Pressure Conditions
17-29
10.1615/AtomizSpr.v21.i1.20
Vital Gutierrez
Fernandez
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), Toulouse, France
Gerard
La VERGNE
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), 31055 Toulouse Cedex 4, France
P.
Berthoumieu
Heterogeneous, Multiphase Flows Unit, Aerodynamic and Energetic Models Department, Office National d'Etudes et de la Recherche Aérospatiales (ONERA), 31055 Toulouse Cedex 4, France
Airblast
Liquid sheet
High Pressure testing
Atomization mechanisms
Ligaments
Transversal wavelength
Image procesing
An experimental study via fast camera visualizations was accomplished to analyze
the primary atomization. The injection device consisted in a planar airblast
atomizer, which generated a 300μ;m thickness liquid sheet. The system considered,
kept its geometry constant, while the fluids flow was modified to produce a wide
range of conditions. This was achieved by adjusting the fluids' momentum flux. In
the case of the gas, both the air velocity across the airblast atomizer and its absolute
pressure were varied. The latter parameter reached a value of 11 bar. Additionally,
two liquids, water and Kerosene Jet A1 were injected at several velocities. The
manuscript includes results for the break-up length, transversal wavelength, and
longitudinal ligaments length. The behaviour of these characteristics was strongly
affected by the atomization mechanism at which they were measured. Consequently,
a set of image proceses techniques were developed to measure these characteristics.
Finally, a set of empirical relsations are proposed to predict the magnitude of these
characteristics at the tested conditions.
CFD Study of Needle Motion Influence on the Spray Conditions of Single-Hole Injectors
31-40
10.1615/AtomizSpr.v21.i1.30
Xandra
Margot
CMT-Motores Térmicos
Edificio 6D
Universitat Politècnica de València
Camino de Vera s/n
46022 Valencia. Spain
Sergio
Hoyas
School of Aeronautics, Universidad Politecnica de Madrid 28040 Madrid, Spain; CMT - Motores Térmicos, Universidad Politécnica de Valencia, Camino de Vera S/N, 46022 Valencia, Spain
P.
Fajardo
CMT - Motores Térmicos, Universidad Politécnica de Valencia, Camino de Vera S/N, 46022 Valencia, Spain
S.
Patouna
CMT - Motores Térmicos, Universidad Politécnica de Valencia, Camino de Vera S/N, 46022 Valencia, Spain
CFD; Cavitation; Moving Mesh; Spray Conditions; Diesel Injectors
The spray characteristics and consequently the success of the diesel combustion process is strongly affected by the manner in which fuel is introduced in the combustion chamber. This work consists in studying the effect of needle motion of typical single-hole sac-type injectors on nozzle exit conditions. Three-dimensional moving mesh simulations have been carried out to calculate the injection process using cylindrical and conical nozzle geometries. The CFD analysis includes a study of the effect of cavitation on kinetic turbulent energy and velocity profiles. Results show that the flow within the nozzle and at the exit varies depending on the nozzle geometry and needle position. The model predicts clouds of cavitation that grow and exit the nozzle at low needle lifts. A kind of hysteresis in the development of the flow has also been observed between needle opening and closing. The existing correlation between turbulence and cavitation at the nozzle hole exit during the needle motion has been quantified.
Subgrid analysis of liquid jet atomization
41-67
10.1615/AtomizSpr.v21.i1.40
J.
Chesnel
CORIA UMR 6614, University of Rouen, Technopole du Madrillet, BP 12, 76801 Saint-Etienne-du-Rouvray Cedex, France
Thibaut
Menard
CNRS, CORIA UMR 6614, University of Rouen, Technopole du Madrillet, BP 12, 76801 Saint- Etienne-du-Rouvray Cedex, France
Julien
Reveillon
CORIA-UMR 6614 – Normandie Université, CNRS-Université et INSA de
Rouen, Campus Universitaire du Madrillet, 76800 Saint Etienne du Rouvray,
France
Francois-Xavier
Demoulin
CORIA-UMR 6614 – Normandie Université, CNRS-Université et INSA de
Rouen, Campus Universitaire du Madrillet, 76800 Saint Etienne du Rouvray,
France
atomization
subgrid modeling
Large Eddy Simulation
two-phase flow
Direct numerical simulation
The objective of this paper is to study the feasibility of large eddy simulations of
a liquid fuel injection in combustion chambers. To do so, a priori analyses of direct
numerical simulations are carried out. A complete liquid jet atomization, from the
injector down to the end of the liquid core, is simulated thanks to the coupling of
both level-set and VOF formulations. To avoid the apparition of a subgrid term
in the right hand side of the continuity equation, the choice was made to consider
an incompressible formulation as far as the filtering operator is concerned. The
corresponding LES transport equations and various subgrid contributions are thus
presented. Results are first dedicated to the estimation of the various orders of
magnitude of these subgrid terms. In a second part, classical eddy viscosity scale
similarity models are tested against the prevalent ones. It appears that, contrary
to a Smagorinsky formulation, the scale similarity assumption provides a better
estimation of the subgrid terms. This result is found for all locations that have been
considered in the jet: at the injection level or in the atomized area. The major
drawback is the presence of a constant that needs to be estimated. Various values
are found depending on the filter size.
The Delay Phenomena in Thermal Explosion of Polydisperse Fuel Spray: Asymptotic Analysis
69-85
10.1615/AtomizSpr.v21.i1.50
OPhir
Nave
Ben-Gurion University of the Negev
Vladimir
Gol'dshtein
Department of Mathematics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
Eitan
Dan
Elbit Systems, Ltd., The International of Defense Electronics Company, Haifa 31053, Israel
Diesel engines
Thermal Radiation
Method of integral manifolds
probability density function
In this paper we investigate the problem of thermal explosion in a two-phase polydisperse combustible mixture. The model for the radiative heating of droplets takes into account the semi transparency of the droplets. The numerical results of the analysis are applied to the modeling of thermal explosion in diesel engines. The current work presents a new, simplified model of the thermal explosion in a combustible gaseous mixture containing vaporizing fuel droplets of different radii (polydisperse). The polydispersity is modeled using a Probability Density Function (PDF) that corresponds to the initial distribution of fuel droplets. An explicit expression of the critical condition for thermal explosion limit is derived analytically and represent a generalization of the critical parameter of the classical Semenov theory.
How Vegetable Oils and Its Derivatives Affect Spray Characteristics in CI Engines- A Review
87-105
10.1615/AtomizSpr.v21.i1.60
Soo-Young
No
Dept. of Biosystems Engineering, Dept of Agricultural Machinery Engineering, Chungbuk National University, South Korea
vegetable oil
biodiesel
spray angle
spray penetration
liquid penetration
SMD
CI engine
Even though there are so many articles related to the review on production of biodiesels from edible and in-edible vegetable oils, performance and exhaust emissions of compression ignition(CI) engines fuelled with vege-table oil and its derivatives, the effect of vegetable oils and its derivatives on spray characteristics was not con-sidered in those reviews. High viscosity of vegetable oils and its derivatives is one of the main problems in the application to CI engine as substitute fuel. Therefore, how vegetable oils and its derivatives affect spray charac-teristics, mainly related to fuel viscosity, in CI engines fuelled with vegetable oils and its derivatives is the main concern in this study. Of edible vegetable oils, soybean, rapeseed and palm oils were mainly investigated. Of inedible vegetable oils, jatropha, karanja, rubber seed and used cooking oils were main concern on the research of the spray characteristics in CI engine. Spray angle, spray penetration and liquid phase penetration were mainly examined among the macroscopic spray characteristics and Sauter mean diameter was only investigated among the microscopic spray characteristics. It was found that so many different definitions of spray angle were suggested by various researchers. The empirical correlation, which is different with existing ones, for the calculation of spray penetration for biodiesel in the early stage of injection was newly suggested. The original vegetable oil for the production of biodiesel affects the spray characteristics and quality of atomization.