scholarly journals Modeling the Formation of Urea-Water Sprays from an Air-Assisted Nozzle

2020 ◽  
Vol 10 (16) ◽  
pp. 5723
Author(s):  
Jens Frühhaber ◽  
Christian Lieber ◽  
Dominik Mattes ◽  
Thomas Lauer ◽  
Rainer Koch ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Turbulent Dispersion ◽  
Size Distributions ◽  
Two Phase ◽  
Validation Data ◽  
Spray Formation ◽  
Fine Spray ◽  
Computational Fluid Dynamics Cfd ◽  
Breakup Model ◽  
Droplet Size Distributions

Ammonia preparation from urea-water solutions is a key feature to ensure an effective reduction of nitrogen oxides in selective catalytic reduction (SCR) systems. Thereby, air-assisted nozzles provide fine sprays, which enhance ammonia homogenization. In the present study, a methodology was developed to model the spray formation by means of computational fluid dynamics (CFD) for this type of atomizer. Experimental validation data was generated in an optically accessible hot gas test bench using a shadowgraphy setup providing droplet velocities and size distributions at designated positions inside the duct. An adaption of the turbulence model was performed in order to correct the dispersion of the turbulent gas jet. The spray modeling in the near nozzle region is based on an experimentally determined droplet spectrum in combination with the WAVE breakup model. This methodology was applied due to the fact that the emerging two-phase flow will immediately disintegrate into a fine spray downstream the nozzle exit, which is also known from cavitating diesel nozzles. The suitability of this approach was validated against the radial velocity and droplet size distributions at the first measurement position downstream the nozzle. In addition, the simulation results serve as a basis for the investigation of turbulent dispersion phenomena and evaporation inside the spray.

scholarly journals An Experimental Data Base for the Computational Fluid Dynamics of Reacting and Nonreacting Methanol Sprays

1995 ◽  
Vol 117 (1) ◽  
pp. 145-153 ◽  
Author(s):  
V. G. McDonell ◽  
G. S. Samuelsen
Keyword(s):  
Data Base ◽  
Gas Phase ◽  
Vapor Concentration ◽  
Data Sets ◽  
Size Distributions ◽  
Two Phase ◽  
Data Set ◽  
Phase Velocities ◽  
Spray Structure ◽  
Droplet Size Distributions

The present data set consists of detailed measurements obtained within methanol sprays produced by a research atomizer which is operated with three atomizing air modes: none, non-swirling, and swirling. In addition, the cases with nonswirling and swirling atomizing air are characterized under reacting conditions. In each case, state-of-the-art diagnostics are applied. Measurements of the gas phase velocities in both the single and two-phase cases, droplet size distributions, and vapor concentration are obtained. The data are reported in a standardized format to ensure usefulness as modeling challenges. The results obtained reveal the presence of significant interaction between phases and significant changes in spray structure as a result of altering the atomizing air characteristics. Efforts have been directed toward delineation of errors and comparison with existing data sets where possible. The results is a comprehensive data base for vaporizing sprays under reacting and non-reacting conditions which permit a systematic variation in aerodynamic effects to be explored.

Dynamics of Intermittent Sprays

1999 ◽  
Author(s):  
Badih A. Jawad
Keyword(s):  
Droplet Size ◽  
Droplet Size Distribution ◽  
Sampling Technique ◽  
Size Distributions ◽  
Ambient Conditions ◽  
Spray Formation ◽  
Fuel Droplets ◽  
Liquid Immersion ◽  
Particle Sizer ◽  
Droplet Size Distributions

Abstract It is considered that droplet size distribution changes with time and space, since diesel fuel sprays are found to be transient and intermittent due to variations in ambient pressures. Therefore the obscuration signal (extinction of light due to particle field) obtained from a particle sizer for a single injection of fuel over the whole region of spray is necessary to determine the spray characteristics. Previous studies dealing with sprays have observed fuel droplets by use of the sedimentation tower method or liquid immersion sampling technique. However, in these technique droplets are usually sampled after spray formation is complete. The completion time of spray formation appears to vary with ambient conditions, thus making spray measurements under transient conditions during injection difficult. It is the objective of this paper to shine some light on the dynamics of spray motion, leading to a better understanding of the droplet size distributions.

scholarly journals The fragmentation of the ocean: spray formation

2012 ◽  
Vol 696 ◽  
pp. 1-4 ◽  
Author(s):  
Yves Couder
Keyword(s):  
Complex System ◽  
Field Measurements ◽  
Single Type ◽  
Sea Spray ◽  
Size Distributions ◽  
Spray Formation ◽  
System A ◽  
Ocean Spray ◽  
Remarkable Result ◽  
Droplet Size Distributions

AbstractBy what process can droplets be extracted out of the sea? This is an old problem, well-documented by precise field measurements of the size distribution of the spray aerosols. Lhuissier & Villermaux (J. Fluid Mech., this issue, vol. 696, 2012, pp. 5–44) study and characterize the bursting of an emerging bubble. They show that this single type of event can, by itself, generate the droplet size distributions in a sea spray. This is a remarkable result showing how, in a complex system, a statistical distribution can be entirely produced by the dynamics of one dominant phenomenon.

DROPLET SIZE DISTRIBUTIONS OF ADJUVANT-AMENDED SPRAYS FROM AN AIR-ASSISTED FIVE-PORT PWM NOZZLE

2011 ◽  
Vol 21 (3) ◽  
pp. 263-274 ◽  
Author(s):  
Jiabing Gu ◽  
Heping Zhu ◽  
Weimin Ding ◽  
Hong Young Jeon
Keyword(s):  
Droplet Size ◽  
Size Distributions ◽  
Droplet Size Distributions

CONVERSION OF DROPLET SIZE DISTRIBUTIONS FROM PMS OPTICAL ARRAY PROBE TO MALVERN LASER DIFFRACTION

2002 ◽  
Vol 12 (1-3) ◽  
pp. 267-282 ◽  
Author(s):  
Milton E. Teske ◽  
Harold W. Thistle ◽  
Andrew J. Hewitt ◽  
I. W. Kirk
Keyword(s):  
Droplet Size ◽  
Laser Diffraction ◽  
Size Distributions ◽  
Array Probe ◽  
Droplet Size Distributions

EXPERIMENTAL INVESTIGATION, SCALE-UP AND MODELING OF DROPLET SIZE DISTRIBUTIONS IN TURBULENT MULTIPHASE JETS

2020 ◽  
Vol 32 (2) ◽  
pp. 113-136 ◽  
Author(s):  
Simeon Pesch ◽  
Rebecca Knopf ◽  
Anahita Radmehr ◽  
Claire B. Paris ◽  
Zachary M. Aman ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Droplet Size ◽  
Scale Up ◽  
Size Distributions ◽  
Droplet Size Distributions
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