Begell House Inc.
Atomization and Sprays
AAS
1044-5110
29
12
2019
AN IMPLICIT FORMULATION TO MODEL THE EVAPORATION PROCESS IN THE EULERIAN-LAGRANGIAN SPRAY ATOMIZATION (ELSA) FRAMEWORK
1043-1069
10.1615/AtomizSpr.2020032627
Lorenzo
Palanti
Department of Industrial Engineering (DIEF), University of Florence, via S.
Marta 3, Florence 50139, Italy
Stefano
Puggelli
Department of Industrial Engineering (DIEF), University of Florence, via S.
Marta 3, Florence 50139, Italy
A.
Andreini
Department of Industrial Engineering (DIEF), University of Florence, via S.
Marta 3, Florence 50139, Italy
Julien
Reveillon
CORIA-UMR 6614 – Normandie Université, CNRS-Université et INSA de
Rouen, Campus Universitaire du Madrillet, 76800 Saint Etienne du Rouvray,
France
B.
Duret
CORIA-UMR 6614, Normandie University, CNRS-University and INSA of
Rouen, Avenue de l'Université BP 12, Saint-Étienne-du-Rouvray 76800,
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
CFD
sprays
evaporation
dense spray region
Eulerian-Eulerian
ELSA
ECN Spray A
In the present work, an implicit evaporation model for the coherent structures of evaporating sprays is introduced and validated against experimental data of engine combustion network (ECN) spray A. The main aim is to go beyond the limits of standard evaporation models, which are normally based on a dilute spray assumption, and develop a strategy to deal with liquid volume fraction virtually up to one. The proposed method is based on a priori computation of the steady-state equilibrium conditions reached by a system composed by liquid, vapor and air at constant pressure combined with a modeled characteristic time of evaporation. Such equilibrium composition and temperature are then used inside numerical calculations to compute evaporation source terms implemented in an implicit fashion. The new formulation allows simulating evaporation process in the dense zone of the spray, where, due to the extremely low time scales related to mass and heat transfer, classical explicit method usually leads to non-physical results. Such innovative approach has been implemented in a multiphase solver based on the Eulerian-Lagrangian Spray Atomization (ELSA) model in the framework of the computational fluid dynamics (CFD) suite OpenFOAM®. The use of ELSA allows the mass and heat transfer terms to be modeled as a function of the transported amount of liquid-gas interface surface available for evaporation. An analysis of the model performances has been carried out in an URANS framework in order to highlight the physically consistent representation of evaporation phenomena of the approach in the regions characterized by a high liquid volume fraction.
A ROBUST STATISTICAL ALGORITHM FOR BOUNDARY DETECTION IN LIQUID SPRAYS
1071-1085
10.1615/AtomizSpr.2020032584
C. Taber
Wanstall
University of Alabama, Tuscaloosa, AL, 35487, USA; Department of Mechanical and Aerospace Engineering, The University of Dayton, Kettering Laboratories, Room 365, 300 College Park, Dayton, OH, 45469, USA
Henning
Junne
Technische Universitat Berlin, Ackerstrasse 76, 13355 Berlin, Germany
Joshua A.
Bittle
Mechanical Engineering Department, The University of Alabama, 245 7th Ave., 3043 HM Comer, Tuscaloosa, AL, 35487, USA
Ajay K.
Agrawal
Mechanical Engineering Department, The University of Alabama, 245 7th Ave., 3043 HM Comer, Tuscaloosa, AL, 35487, USA
DBI
Mie-scattering
sprays
exposure time
liquid boundary detection
This work presents a statistical algorithm to detect phase boundaries in liquid sprays. Experimental data were obtained in a nonevaporating acetone spray at atmospheric conditions to minimize the refractive index gradients and associated beam steering. Mie scattering and diffuse background illumination
(DBI) diagnostics are implemented to demonstrate the robustness of the approach. The analysis shows that the present algorithm yields similar results for the two different diagnostics, unlike existing threshold-based methodologies providing inconsistent results. The algorithm can be used to identify partial liquid boundaries between single-phase liquid and vapor boundaries. Thus, for each case, liquid boundaries were defined in terms of liquid probability of 100% or less than 100%. Sprays from two different injectors were analyzed to demonstrate the versatility of the methodology. A parametric study was conducted to demonstrate that motion blur can affect an accurate detection of the phase boundaries, and hence, the exposure time in the experiment must be sufficiently small.
ELECTROHYDRODYNAMIC INSTABILITY OF A STREAMING DIELECTRIC VISCOUS LIQUID JET WITH MASS AND HEAT TRANSFER
1087-1108
10.1615/AtomizSpr.2020032603
M. F. E.
Amer
Department of Mathematics, Faculty of Education, Ain Shams University, Heliopolis, Roxy 11757, Cairo, Egypt
Galal M.
Moatimid
Department of Mathematics, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt
hydrodynamic stability
viscous fluids
liquid jets
three-dimensional disturbances
mass and heat transfer
electrohydrodynamics
The current paper investigates the electrohydrodynamic (EHD) instability of a streaming dielectric liquid jet. The inner medium is occupied by an incompressible Newtonian viscous fluid. Simultane-ously, the outer medium is filled with an incompressible gas. The system is pervaded by a uniform
axial electrostatic field. The mass and heat transfer phenomenon is taken into account. In order to relax the mathematical manipulation, a simplified modulation of this system is adopted. The normal modes analysis is utilized to solve the boundary-value problem and to judge the linear stability of the system. A non-dimensional treatment reveals two non-dimensional numbers:Weber and Ohnesorge. The linear stability analysis resulted in a very complicated transcendental dispersion equation. The same numbers are considered with regard to the temporal and spatial increase of both frequency and modulation. The influences of various physical parameters in the stability profile are exercised as
well. It is found that the velocity ratio between gas to liquid has a dual role in the stability profile. Moreover, the Weber number has a destabilizing effect, which produces a higher growth rate and, thus, shorter breakup time. In addition, the presence of the electric field as well as the mass and heat
transfer stabilize the viscous liquid jet. Furthermore, the viscous effect as indicated by the Ohnesorge number has a stabilized influence. The present work gives a good foundation of the investigation of the instability and breakup of a viscous liquid jet with electric field effect and mass and heat transfer existence.
EXPERIMENTAL INVESTIGATION OF SPRAY CHARACTERISTICS OF MULTI-HOLE AND SLOT GDI INJECTORS AT VARIOUS FUEL TEMPERATURES USING CLOSELY SPACED SPLIT-INJECTION STRATEGIES
1109-1131
10.1615/AtomizSpr.2020033439
Shengqi
Wu
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, 48109, USA; Powertrain Research and Advanced Engineering, Ford Motor Company, Dearborn, Michigan, 48124, USA
Mark
Meinhart
Powertrain Research and Advanced Engineering, Ford Motor Company, Dearborn, Michigan, 48124, USA
Jianwen
Yi
Powertrain Research and Advanced Engineering, Ford Motor Company, Dearborn, Michigan, 48124, USA
GDI multi-hole injector
GDI slot injector
flash boiling spray
global spray structure
overpenetration
split injection
In this study, multi-hole and slot gasoline direct-injection (GDI) injectors were investigated at various fuel temperatures by using various closely spaced split-injection strategies. The four tested injectors were a six-hole injector, a four-slot injector, a three-slot injector, and a one-slot injector.
N-heptane was chosen as the test fuel, and fuel temperature ranged from 25°C to 130°C. Various closely coupled split-injection strategies were investigated, including single injection, double injection, triple injection, and quadruple injection. Results showed that fuel temperature had a negligible effect on global spray structure when fuel vapor pressure was lower than the ambient pressure, and spray structure was mainly dominated by injector configuration. Spray collapse occurred at strong superheated conditions of all injectors, which altered spray structure and, consequently, the fuel distribution. However, different trends of spray penetration caused by spray collapse were observed. Strong spray collapse led to increased spray penetration of the six-hole injector; but for the slot injectors, spray penetration was smaller than that at cold fuel temperature even when strong spray collapse occurred. By using quadruple-injection strategy, penetration of strong collapsed fuel spray was even shorter than that of fuel spray at 25°C fuel temperature of single injection of the six-hole injector. Finally, it can be concluded that by using special injector configuration or split-injection strategy, the overpenetrating issue caused by strong spray collapse at high fuel temperatures of multi-hole GDI injectors can be mitigated or avoided.
INDEX, VOLUME 29, 2019
1133-1140
10.1615/AtomizSpr.v29.i12.50