Experimental and numerical investigation of the primary breakup of an airblasted liquid sheet

2017 ◽  
Vol 91 ◽  
pp. 208-224 ◽  
Author(s):  
K. Warncke ◽  
S. Gepperth ◽  
B. Sauer ◽  
A. Sadiki ◽  
J. Janicka ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Liquid Sheet ◽  
Primary Breakup

scholarly journals Progress in the Smoothed Particle Hydrodynamics Method to Simulate and Post-process Numerical Simulations of Annular Airblast Atomizers

2020 ◽  
Vol 105 (4) ◽  
pp. 1119-1147
Author(s):  
G. Chaussonnet ◽  
T. Dauch ◽  
M. Keller ◽  
M. Okraschevski ◽  
C. Ates ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Flux Ratio ◽  
Liquid Sheet ◽  
Sph Method ◽  
Post Process ◽  
Finite Time Lyapunov Exponent ◽  
Fragmentation Spectrum ◽  
Particle Hydrodynamics ◽  
Primary Breakup ◽  
Smoothed Particle

AbstractThis paper illustrates recent progresses in the development of the smoothed particle hydrodynamics (SPH) method to simulate and post-process liquid spray generation. The simulation of a generic annular airblast atomizer is presented, in which a liquid sheet is fragmented by two concentric counter swirling air streams. The accent is put on how the SPH method can bridge the gap between the CAD geometry of a nozzle and its characterization, in terms of spray characteristics and dynamics. In addition, the Lagrangian nature of the SPH method allows to extract additional data to give further insight in the spraying process. First, the sequential breakup events can be tracked from one large liquid blob to very fine stable droplets. This is herein called the tree of fragmentation. From this tree of fragmentation, abstract quantities can be drawn such as the breakup activity and the fragmentation spectrum. Second, the Lagrangian coherent structures in the turbulent flow can be determined easily with the finite-time Lyapunov exponent (FTLE). The extraction of the FTLE is particularly feasible in the SPH framework. Finally, it is pointed out that there is no universal and ultimate non-dimensional number that can characterize airblast primary breakup. Depending on the field of interest, a non-dimensional number (e.g. Weber number) might be more appropriate than another one (e.g. momentum flux ratio) to characterize the regime, and vice versa.

The Effect of Crosswind Velocity on the Spray Drift of Flat Fan Nozzle

2019 ◽  
Author(s):  
S. Raza ◽  
K. A. Sallam ◽  
S. L. Post
Keyword(s):  
Liquid Sheet ◽  
Nozzle Geometry ◽  
Target Area ◽  
Spray Drift ◽  
Agricultural Industry ◽  
Injection Angle ◽  
Drift Flux ◽  
Breakup Mechanism ◽  
Primary Breakup ◽  
Sheet Breakup

Abstract The objective of this research project is to eliminate the spray drift caused by crosswind. Spray drift is an important problem for the agricultural industry. Some herbicides (e.g. Dicamba) can cause serious damage if it drifts to nearby crops that are not genetically modified to withstand those herbicides. Our hypothesis is that the nozzle geometry and the injection angle can be actively/passively controlled to compensate for the crosswind velocity and effectively deliver the herbicides to the target area. The measurements include the breakup regime transitions, the droplet sizes, and the droplets trajectory as function of the wind speed and the injection angle. The current results show that the crosswind modifies the primary breakup mechanism from sheet breakup regime (i.e. thinning and fragmentation of the liquid sheet into ligaments) to bag breakup regime (i.e. the formation bags along the downstream side of liquid sheet) resulting in smaller drop sizes and an increased drift flux. Techniques to eliminate the bag breakup regime are presented.

scholarly journals Numerical investigation of turbulent-jet primary breakup using one-dimensional turbulence

2017 ◽  
Vol 89 ◽  
pp. 241-254 ◽  
Author(s):  
A. Movaghar ◽  
M. Linne ◽  
M. Oevermann ◽  
F. Meiselbach ◽  
H. Schmidt ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Turbulent Jet ◽  
One Dimensional ◽  
Primary Breakup

Numerical investigation into primary breakup of diesel spray with residual bubbles in the nozzle

Fuel ◽  
2019 ◽  
Vol 250 ◽  
pp. 265-276 ◽  
Author(s):  
Weilong Zhang ◽  
Hong Liu ◽  
Canxu Liu ◽  
Ming Jia ◽  
Xi Xi
Keyword(s):  
Numerical Investigation ◽  
Diesel Spray ◽  
Primary Breakup

Numerical Investigation on Primary Atomization of the Fuel Spray in Diesel Engines

2012 ◽  
Vol 516-517 ◽  
pp. 634-637
Author(s):  
Zhi Xia He ◽  
Li Li Tian ◽  
Ju Yan Liu
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Investigation ◽  
Diesel Engines ◽  
Fuel Spray ◽  
New Model ◽  
Turbulence Flow ◽  
Primary Breakup ◽  
Simulation Results ◽  
Breakup Model

In addition to the aerodynamic effects, turbulence and cavitation play an important role on the primary atomization. Different spray breakup models were analysized and evaluated though simulation of spray with them and then a new model of coupling the nozzle cavitating and turbulence flow to the spray primary breakup was put forward. The numerical simulation results with all these different spray primary breakup models were comparied with the experimental data and then the new model were proved to be much better. The study may effectively help establish the accurate spray breakup model.

Numerical Investigation of the Unstable Wave on a Planar Liquid Sheet Produced by an Air-Blast Atomizer

2014 ◽  
Author(s):  
Hua Zhou ◽  
Chia-fon F. Lee ◽  
Timothy H. Lee
Keyword(s):  
Relative Motion ◽  
Internal Flow ◽  
Particle Method ◽  
Liquid Sheet ◽  
Shear Instability ◽  
Unstable Wave ◽  
Air Blast ◽  
Primary Breakup ◽  
Specific Frequency ◽  
Fluid Particles

The unstable surface wave on a liquid sheet produced by an air-blast atomizer during primary breakup process was investigated by numerical simulation. The results of simulation were verified by comparison of primary breakup time and breakup length with accessible experimental data reported in technical papers. The frequency characteristics of stream-wise unstable wave at different axial locations were investigated by applying Discrete Fourier Transform (DFT). It was found that when there is no disturbance induced by internal flow, there is no specific frequency which is favored by shear instability near the nozzle exit, and the characteristic frequency of the dominant wave decreases along stream-wise direction due to the decrease of relative velocity. By applying Discrete Particle Method (DPM), the motion of fluid particles inside the liquid sheet was able to be tracked, and the Lagrangian characteristics of fluid particles can be partially revealed. The growth of stream-wise unstable wave was found to possess strong spatial characteristics by investigating the pathlines and streaklines of fluid particles. A rough evaluation for the stream-wise speed of fluid particles and the propagation velocity of unstable wave showed that fluid particles move faster than unstable wave in stream-wise direction, thus, relative motion exists between fluid particles and stream-wise wave. This relative motion could lead to huge acceleration of fluid particles, which could trigger Rayleigh-Taylor (RT) instability to induce transverse disintegration. Some complex behaviors of fluid particles inside the liquid sheet were observed, e.g. eddy-like structures formed by fluid particles.

Numerical study of the primary breakup of a plane liquid sheet with co-flowing air streams

PAMM ◽  
2012 ◽  
Vol 12 (1) ◽  
pp. 513-514
Author(s):  
Suresh kumar Kannan ◽  
Bernhard Peters
Keyword(s):  
Numerical Study ◽  
Liquid Sheet ◽  
Primary Breakup ◽  
Air Streams

A Functional Correlation for the Primary Breakup Processes of Liquid Sheets Emerging From Air-Assist Atomizers

2006 ◽  
Vol 129 (2) ◽  
pp. 188-193 ◽  
Author(s):  
V. Sivadas ◽  
M. V. Heitor ◽  
Rui Fernandes
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
Flux Ratio ◽  
Liquid Sheet ◽  
Spray Angle ◽  
High Speed Imaging ◽  
Liquid Sheets ◽  
Primary Breakup ◽  
Sheet Breakup ◽  
The Stability

The study aims to highlight a general relationship between the characteristic variables of liquid sheet breakup and the principal forces of the flow domain. To accomplish this objective, an experimental investigation on air-assisted liquid sheets was carried out for a range of liquid-to-air velocities. The associated spray angle, breakup frequency, and breakup length were measured by exploiting high-speed imaging techniques. The results demonstrate that, when the stability variables are related to the liquid–air momentum flux ratio, a high correlation was attained for a range of flow conditions where capillary instability is insignificant.

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