scholarly journals Breakup Processes and Droplet Characteristics of Liquid Jets Injected into Low-Speed Air Crossflow

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 676
Author(s):  
Lingzhen Kong ◽  
Tian Lan ◽  
Jiaqing Chen ◽  
Kuisheng Wang ◽  
Huan Sun
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Weber Number ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Liquid Jet ◽  
Outlet Section ◽  
Low Speed ◽  
Jet Breakup ◽  
Breakup Mode

The breakup processes and droplet characteristics of a liquid jet injected into a low-speed air crossflow in the finite space were experimentally investigated. The liquid jet breakup processes were recorded by high-speed photography, and phase-Doppler anemometry (PDA) was employed to measure the droplet sizes and droplet velocities. Through the instantaneous image observation, the liquid jet breakup mode could be divided into bump breakup, arcade breakup and bag breakup modes, and the experimental regime map of primary breakup processes was summarized. The transition boundaries between different breakup modes were found. The gas Weber number (Weg) could be considered as the most sensitive dimensionless parameter for the breakup mode. There was a Weg transition point, and droplet size distribution was able to change from the oblique-I-type to the C-type with an increase in Weg. The liquid jet Weber number (Wej) had little effect on droplet size distribution, and droplet size was in the range of 50–150 μm. If Weg > 7.55, the atomization efficiency would be very considerable. Droplet velocity increased significantly with an increase in Weg of the air crossflow, but the change in droplet velocity was not obvious with the increase in Wej. Weg had a decisive effect on the droplet velocity distribution in the outlet section of test tube.

Numerical Simulation and Experiment of Atomization Field of Fan-Shaped Atomization Nozzle for Plant Protection UAV

2021 ◽  
Vol 14 ◽  
Author(s):  
Maohua Xiao ◽  
Yuanfang Zhao ◽  
Zhenmin Sun ◽  
Chaohui Liu ◽  
Tianpeng Zhang
Keyword(s):  
Numerical Simulation ◽  
Size Distribution ◽  
Droplet Size ◽  
Plant Protection ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Spray Cone Angle ◽  
Spray Cone

Background: There are drift and volatilization of the droplets produced by the plant protection Unmanned Aerial Vehicle (UAV) under the influence of external wind speed and its flight speed. Objective: It studied the atomization characteristics of its fan-shaped atomizing nozzle under different inlet pressures and inner cavity diameters. Methods: For the start, the Realizable k-ε turbulence model, DPM discrete phase model and TAB breakup model are used to make a numerical simulation of the spray process of the nozzle. Then, the SIMPLE algorithm is used to obtain the droplet size distribution diagram of the nozzle atomization field. At last, the related test methods are used to study its atomization performance, and the changes of atomization angle and droplet velocity under different inlet pressures and inner cavity diameters and the distribution of droplet size are discussed. Results: The research results show that under the same inner cavity diameter, as the inlet pressure increases, the spray cone angle of the nozzle and the droplet velocity at the same distance from the nozzle increase. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of small diameter, and the droplets in the anti-drift droplet size area increase. Under the same inlet pressure, as the diameter of the inner cavity increases, the spray cone angle first increases and then decreases, and the droplet velocity at the same distance from the nozzle increases. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of large diameter, and the large size droplets increase, which cannot meet the anti-drift volatilization effect. Conclusion: Under the parameter set in this study, when the inlet pressure is 0.6MPa and the inner cavity diameter is 2mm, the atomization result is the best.

Droplet Size Distributions and Pressure Control in the Gas-Liquid Cylindrical Cyclone

2020 ◽  
Author(s):  
Lele Yang ◽  
Jing Wang ◽  
Li Zou
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Flow Instability ◽  
Droplet Size Distribution ◽  
Pressure Control ◽  
Superficial Velocity ◽  
Liquid Level ◽  
Outlet Section ◽  
Cylindrical Cyclone

Abstract The gas–liquid cylindrical cyclone (GLCC) employs gravitational and centrifugal forces to realize gas-liquid separation. The aim of this study is to understand the droplet size distribution and pressure control in the GLCC via experiment and numerical analysis. The droplet size and pressure distributions were measured using Malvern RTsizer and pressure transmitters, respectively. The Discrete Phase Model was used to numerically analyze the swirling hydrodynamics of the GLCC. The results showed that the increase in the gas superficial velocity decreased the droplet size distribution at the inlet as a whole due to the shear effect and flow instability. The increase in the liquid superficial velocity only increased the small droplet size distribution at the inlet for the limitation of the gas’s carrying capacity. The pressure loss mainly occurred at the inlet and the overflow outlet. When the liquid level was remained below the inlet and above the liquid outlet, the liquid level and the liquid outlet section approximately met the Bernoulli equation for a finite large flow beam. With the increase in the pressure at the gas outlet, the liquid film fell back and the separation efficiency increased gradually. These results are helpful for further spreading applications of the GLCC in industry.

Investigation of jet breakup and droplet size distribution of liquid CO2and water systems—implications for CO2hydrate formation for ocean carbon sequestration

2004 ◽  
Vol 89 (8-9) ◽  
pp. 1240-1246 ◽  
Author(s):  
David Riestenberg ◽  
Elizabeth Chiu ◽  
Monsuru Gborigi ◽  
Liyuan Liang ◽  
Olivia R. West ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Water Systems ◽  
Jet Breakup ◽  
Ocean Carbon

scholarly journals Experimental Study of the Effect of the Expansion Segment Geometry on the Atomization of a Plain-Jet Airblast Atomizer

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yi Jin ◽  
Kanghong Yao ◽  
Xiaomin He ◽  
Kai Zhang ◽  
Yunbiao Wang
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Geometrical Parameters ◽  
Distribution Factor ◽  
Sauter Mean Diameter ◽  
Mean Velocity ◽  
Expansion Segment ◽  
Mean Diameter

In this paper, the idea of adding an expansion segment over traditional airblast atomizer is proposed to improve the spray performance. According to the systematic experiments, the Sauter mean diameter, the droplet size distribution, and the droplet axial mean velocity were obtained to evaluate the spray performance. The correlations between spray performance and four geometrical parameters of the expansion segment which include the length, the angle, the throat area, and position of liquid jet are considered. The atomizer operates at atmospheric pressure and temperature, and the air liquid ratio range is from 0.48 to 2.85. The data of the results were measured by Phase Doppler Particle Analyzer. The results show that more uniform droplet size distribution can be achieved with the addition of expansion segment, and the droplet size distribution factor q of the case adding the expansion segment is 52.8% bigger than that of the case with no expansion segment. q increases as the length and angle of expansion segment increase. The Sauter mean diameter can be reduced by either reducing the length or angle of expansion segment. As for droplet velocity, it is determined that the droplet velocity increases along the radial direction, which is noteworthy because opposite trend is reported for traditional plain-jet atomizers. With an increase of the length, angle, and throat area of the expansion segment, the droplet axial velocity decays.

Numerical Analysis of Droplet Size Distribution Using Particle Method

2003 ◽  
Author(s):  
K. Shibata ◽  
S. Koshizuka ◽  
Y. Oka
Keyword(s):  
Numerical Analysis ◽  
Size Distribution ◽  
Weber Number ◽  
Incompressible Flows ◽  
Droplet Size Distribution ◽  
Particle Method ◽  
Correlation Effects ◽  
Jet Breakup ◽  
Experimental Correlation ◽  
Moving Particle

A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution which has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained from the calculation.

Formation and Breakup of Liquid Jets Curved by Gravity

2017 ◽  
Author(s):  
Manash Pratim Borthakur ◽  
Binita Nath ◽  
Gautam Biswas ◽  
Dipankar Bandyopadhyay
Keyword(s):  
Weber Number ◽  
Droplet Size Distribution ◽  
Bond Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Horizontal Distance ◽  
Ohnesorge Number ◽  
Jet Breakup ◽  
Jet Trajectory ◽  
Vertical Height

The formation and breakup of a liquid jet in air with gravity acting perpendicular to the direction of the jet is studied computationally. The liquid jet follows a parabolic path due to the influence of gravity which curves the jet trajectory. Both symmetric and asymmetric perturbations develop on the liquid surface which lead to jet breakup with varying droplet size distribution. The limiting length of the jet at breakup increases with increase in the Weber number and Ohnesorge number. At higher value of Weber number, the liquid jet traverses a longer horizontal distance when released from the same vertical height. Increasing the Bond number leads to a significant increase in the curvature of the jet trajectory. The volume of drops produced varies temporally for a given Weber number and decreases with the increasing value of Weber number. The detached drops undergo rolling motion as well as shape oscillations as they continue to fall on their trajectories.

MODELING DROPLET SIZE DISTRIBUTION NEAR A NOZZLE OUTLET IN AN ICING WIND TUNNEL

2006 ◽  
Vol 16 (6) ◽  
pp. 673-686 ◽  
Author(s):  
Laszlo E. Kollar ◽  
Masoud Farzaneh ◽  
Anatolij R. Karev
Keyword(s):  
Wind Tunnel ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Nozzle Outlet
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