Begell House Inc.
Atomization and Sprays
AAS
1044-5110
30
5
2020
PREFACE: ILASS 2020 SPECIAL ISSUE
v
10.1615/AtomizSpr.2020036131
Mark
Owkes
Department of Mechanical and Industrial Engineering, Montana State
University, Bozeman, MT, 59717-3800, USA
Kyle M.
Bade
Spray Analysis and Research Services, Spraying System Co., Rockford, MI,
49341, USA
Preface to Special Issue
A COMPUTATIONAL PROTOCOL FOR SIMULATION OF LIQUID JETS IN CROSSFLOWS WITH ATOMIZATION
319-330
10.1615/AtomizSpr.2020034815
T.-W.
Lee
Department of Mechanical and Aerospace Engineering, School of Engineering for Matter, Transport and Energy (SEMTE), Arizona State University, Tempe, AZ 85287, USA
B.
Greenlee
Mechanical and Aerospace Engineering, School for Engineering of Matter,
Transport, and Energy (SEMTE), Arizona State University,
Tempe, AZ 85287-6106, USA
J. E.
Park
Mechanical and Aerospace Engineering, School for Engineering of Matter,
Transport, and Energy (SEMTE), Arizona State University,
Tempe, AZ 85287-6106, USA
Hana
Bellerova
Heat Laboratory, Brno University of Technology, Brno, Czech Republic
Miroslav
Raudensky
Heat Transfer and Fluid Flow Laboratory, Faculty of Mechanical Engineering, Brno University of
Technology, Technicka 2, Brno, 616 69, Czech Republic
crossflow
computational fluid dynamics
spray flows
atomization
A new computational procedure for simulating liquid jets in crossflows with atomization is described and demonstrated. In our previous work, the integral form of the conservation equations has been used to derive explicit quadratic formulas for drop size during spray atomization in various geometries. This formula relates the drop size with the local kinetic energy state, i.e., the velocities, so that local velocity data from liquid-phase simulation prior to atomization can be used to determine the initial drop size. This initial drop size and appropriately sampled local gas velocities are used as the initial conditions in the dispersed-phase simulation. This procedure has been performed with good validation and comparison with experimental data at realistic Reynolds and Weber number conditions. This approach is based on the conservation principles and is generalizable so that it can easily be implemented in any spray geometries for accurate and efficient computations of spray flows.
EXPLORATION OF WATER JETS IN SUPERSONIC CROSSFLOW USING X-RAY DIAGNOSTICS
331-350
10.1615/AtomizSpr.2020034448
Kuo-Cheng
Lin
Taitech, Inc., Beavercreek, Ohio 45430, USA
Alan L.
Kastengren
X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA; Combat Capabilities Development Command Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA
Stephen
Hammack
Air Force Research Laboratory, Aerospace Systems Directorate,
Wright-Patterson AFB, Ohio 45433, USA
Campbell
Carter
Air Force Research Laboratory, Aerospace Systems Directorate,
Wright-Patterson AFB, Ohio 45433, USA
supersonic crossflow
x-ray fluorescence
x-ray imaging
Near-field structures of pure- and aerated-liquid jets injected into Mach 2 crossflow environments were experimentally investigated at the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory using high-speed shadowgraph imaging, high-speed x-ray imaging, and pathlength-integrated x-ray fluorescence. Liquid was flush injected into a blowdown supersonic wind tunnel. Test section top and side windows were fitted with a polycarbonate plate for high x-ray transmittance. An axisymmetric aerated-liquid injector was fitted with an exchangeable nozzle adaptor to generate a liquid jet. Water and nitrogen, the gas used for aerated-liquid jets, were doped with specially selected dopants to facilitate x-ray measurements. Liquid column structures for a pure-liquid jet, typically masked by dense droplet clouds in a supersonic crossflow environment, were visualized with the present x-ray imaging setup. Surface-wave formation, movement, and transformation on the column windward surface of the pure-liquid jet, along with column deformation and breakup processes, were qualitatively characterized. We measured time-averaged line-of-sight (LOS) liquid mass distributions within the liquid jet near fields. Cross-sectional liquid column contours of pure-liquid jets at various deformation stages were reconstructed from LOS liquid mass distributions. The pure-liquid jet deformed liquid column reached a maximum width of 1.47 times the orifice diameter before exhibiting rapid mass removal. We also observed the plume-crossing phenomenon in the aerated-liquid jet.
INFLUENCE OF FLASH BOILING ON SPRAY MORPHOLOGY USING A PROTOTYPE INJECTOR FOR GASOLINE COMPRESSION IGNITION (GCI) APPLICATION
351-369
10.1615/AtomizSpr.2020034561
Jianguo
Du
Clean Combustion Research Center, King Abdullah University of Science and
Technology, Thuwal, Makkah Province, Saudi Arabia
Balaji
Mohan
Clean Combustion Research Center, King Abdullah University of Science and
Technology, Thuwal, Makkah Province, Saudi Arabia; Transport Technologies Division, R&DC, Saudi Aramco, Dhahran, Eastern
Province, Saudi Arabia
Jaeheon
Sim
Transport Technologies Division, R&DC, Saudi Aramco, Dhahran, Eastern
Province, Saudi Arabia
Tiegang
Fang
Department of Mechanical and Aerospace Engineering, North Carolina State University, 911 Oval Drive–Campus Box 7910, Raleigh, NC 27695, USA
Junseok
Chang
Transport Technologies Division, R&DC, Saudi Aramco, Dhahran, Eastern
Province, Saudi Arabia
William L.
Roberts
Mechanical Engineering, KAUST Clean Combustion Center, King Abdullah University of Science and Technology, Thuwal 23955, Kingdom of Saudi Arabia
diffused backlit illumination (DBI)
mie scattering
shadowgraph imaging
front and side view simultaneous imaging
Flash boiling occurs with gasoline direct injection spray at throttling, and low-load engine conditions leading to plume interactions and sprays collapse under low ambient densities. The change of fuel trajectory compared with the injector's initial design could leave an adverse effect on spray combustion quality, although flash boiling has the potential of achieving better atomization. Thus, studies on the plume to plume interactions and spray collapse processes are of high importance. Researches have mostly been carried out focusing on the plume interactions in the liquid phase, while in the flash boiling condition, the vapor phase of fuel is nonnegligible. This work focusses on the plume to plume interactions considering both the vapor and liquid phase of the fuel under specific throttling conditions in gasoline compression ignition (GCI) engines using a high-pressure wide spray angle prototype injector. The experiments were carried out at a wide range of pressure ratio (Rp) conditions (Rp = 0.05 to 1.4). Simultaneous front view and side view shadowgraph techniques were implemented to visualize the liquid & vapor phase of the fuel spray. Similarly, simultaneous front view Mie scattering and side view diffused backlit illumination (DBI) techniques were implemented to visualize the liquid phase of the fuel spray. Due to the line of sight plume overlapping at the side view, the difference in spray morphology obtained by DBI and shadowgraph is not apparent. However, the front view comparison shows that, in the transition regime, the plume to plume interactions in the vapor phase are more evident than that in the liquid phase. This work reveals that the front view techniques could be an excellent way to study multiplume interactions during flash boiling phenomena.
LIQUID SPRAY PENETRATION MEASUREMENTS USING HIGH-SPEED BACKLIGHT ILLUMINATION IMAGING IN A SMALL-BORE COMPRESSION IGNITION ENGINE
371-387
10.1615/AtomizSpr.2020034855
Yilong
Zhang
School of Mechanical and Manufacturing Engineering, The University of New
South Wales, Sydney, NSW, Australia
S.
Meng
School of Mechanical and Manufacturing Engineering, The University of New
South Wales, Sydney, NSW, Australia
Sanghoon
Kook
School of Mechanical and Manufacturing Engineering, The University of New
South Wales, Sydney, NSW, Australia
K. S.
Kim
CCDC Army Research Laboratory, Aberdeen Proving Ground, MD, USA
Chol-Bum
Kweon
Combat Capabilities Development Command Army Research Laboratory,
Aberdeen Proving Ground, Maryland 21005, USA
backlight illumination
liquid spray penetration
ambient gas temperature/density
small-bore engine
transient jet mixing model
The present study optically measures the liquid spray penetration using high-speed backlight illumination imaging in a running small-bore compression-ignition engine. This imaging technique utilizes high-power LED as a light source that is reflected on the flat cylinder head surface except the vaporizing spray region. The boundary detection of this dark region is performed to calculate the spray tip penetration. The liquid spray development was visualized for 3 custom-made fuels exhibiting identical physical properties except the cetane number (CN30, CN40, and CN50) and a range of the distillation curves. Because the applicable injection timing range is more advanced for a lower cetane number fuel and vice versa, it provides an ample opportunity to discuss the effects of varying ambient gas temperature/density on the spray. For all tested conditions, the high-speed backlight illumination imaging was repeated for 30 injections. The results showed similar initial increase of the spray penetration for all tested injection timings and fuels due to the strong injection momentum. However, the later spray penetration showed a measurable variation with the maximum penetration becoming longer for both earlier and later injections off from TDC. The trends indicate increased spray penetration due to decreased mixing-limited vaporization at lower ambient gas temperature/density conditions. This was further supported by longer tip penetration for a fuel with higher distillation temperatures. The trends were successfully predicted using a transient jet mixing model employing discrete control volumes, suggesting indeed mixing-limited vaporization governs the liquid spray penetration in a small-bore engine.