Special Issue "Trends in Spray Atomization"

A special issue of Fluids (ISSN 2311-5521). This special issue belongs to the section "Mathematical and Computational Fluid Mechanics".

Deadline for manuscript submissions: closed (30 May 2021).

Special Issue Editors

Dr. Sadegh Poozesh
E-Mail Website
Guest Editor
Mechanical Engineering Department, Tuskegee University, Tuskegee, AL 36088, USA
Interests: spray atomization; computational fluid dynamics; multiphase physics; particle dispersion systems
Dr. Nelson Akafuah
E-Mail Website
Co-Guest Editor
Mechanical Engineering Department, University of Kentucky, Lexington, KY 40506, USA
Interests: spray painitng; heat transfer & combustion; manufacturing processes & systems
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Special Issue Information

Dear Colleagues,

Spray technology and concepts are encountered in our day-by-day lives, from advanced propulsion systems to human respiratory emissions. This special issue covers the state-of-the-art developments in various spray atomization aspects focused on coating, combustion, powder formulation, and respiratory events-with a special emphasis on the latter. New atomization techniques, characterization means, and novel liquid breakup concepts to unravel pathogen carrier droplet transmission routes, in the face of Covid-19 pandemic, are highly encouraged.

Dr. Sadegh Poozesh
Guest Editor
Dr. Nelson Akafuah
Co-Guest Editor

Manuscript Submission Information

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Keywords

  • Spray atomization
  • Respiratory events
  • Liquid injection
  • Break-up phenomena
  • Droplet formation

Published Papers (3 papers)

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Research

Article
Investigation of Oil Droplet Breakup during Atomization of Emulsions: Comparison of Pressure Swirl and Twin-Fluid Atomizers
Fluids 2021, 6(6), 219; https://doi.org/10.3390/fluids6060219 - 11 Jun 2021
Viewed by 1068
Abstract
The goal of this study was to investigate oil droplet breakup in food emulsions during atomization with pressure swirl (PS), internal mixing (IM), and external mixing (EM) twin-fluid atomizers. By this, new knowledge is provided that facilitates the design of atomization processes, taking [...] Read more.
The goal of this study was to investigate oil droplet breakup in food emulsions during atomization with pressure swirl (PS), internal mixing (IM), and external mixing (EM) twin-fluid atomizers. By this, new knowledge is provided that facilitates the design of atomization processes, taking into account atomization performance as well as product characteristics (oil droplet size). Atomization experiments were performed in pilot plant scale at liquid volume flow rates of 21.8, 28.0, and 33.3 L/h. Corresponding liquid pressures in the range of 50–200 bar and air-to-liquid ratios in the range of 0.03–0.5 were applied. Two approaches were followed: oil droplet breakup was initially compared for conditions by which the same spray droplet sizes were achieved at constant liquid throughput. For all volume flow rates, the strongest oil droplet breakup was obtained with the PS nozzle, followed by the IM and the EM twin-fluid atomizer. In a second approach, the concept of energy density EV was used to characterize the sizes of resulting spray droplets and of the dispersed oil droplets in the spray. For all nozzles, Sauter mean diameters of spray and oil droplets showed a power-law dependency on EV. PS nozzles achieved the smallest spray droplet sizes and the strongest oil droplet breakup for a constant EV. In twin-fluid atomizers, the nozzle type (IM or EM) has a significant influence on the resulting oil droplet size, even when the resulting spray droplet size is independent of this nozzle type. Overall, it was shown that the proposed concept of EV allows formulating process functions that simplify the design of atomization processes regarding both spray and oil droplet sizes. Full article
(This article belongs to the Special Issue Trends in Spray Atomization)
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Article
Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle
Fluids 2020, 5(4), 231; https://doi.org/10.3390/fluids5040231 - 03 Dec 2020
Cited by 1 | Viewed by 684
Abstract
Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form [...] Read more.
Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form of the conservation equations to create a system of equations by solving which, the far-field secondary atomization can be analyzed through predicting droplet size and velocity distributions of the involved phases. To validate the model predictions, experiments are conducted at ambient conditions using water, methanol, and acetone as model fluids with varying formulation properties, such as density, viscosity, and surface tension. Droplet size distribution and velocity are measured with laser diffraction and a high-speed camera, respectively. Finally, an attempt is made to utilize non-scaled parameters to characterize the atomization process, useful for extrapolating the sensitivity analysis to other scales. The merit of this model lies in its simplicity for use in process control and optimization. Full article
(This article belongs to the Special Issue Trends in Spray Atomization)
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Article
Numerical Study of the Effects of Twin-Fluid Atomization on the Suspension Plasma Spraying Process
Fluids 2020, 5(4), 224; https://doi.org/10.3390/fluids5040224 - 28 Nov 2020
Viewed by 725
Abstract
Suspension plasma spraying (SPS) is an effective technique to enhance the quality of the thermal barrier, wear-resistant, corrosion-resistant, and superhydrophobic coatings. To create the suspension in the SPS technique, nano and sub-micron solid particles are added to a base liquid (typically water or [...] Read more.
Suspension plasma spraying (SPS) is an effective technique to enhance the quality of the thermal barrier, wear-resistant, corrosion-resistant, and superhydrophobic coatings. To create the suspension in the SPS technique, nano and sub-micron solid particles are added to a base liquid (typically water or ethanol). Subsequently, by using either a mechanical injection system with a plain orifice or a twin-fluid atomizer (e.g., air-blast or effervescent), the suspension is injected into the high-velocity high-temperature plasma flow. In the present work, we simulate the interactions between the air-blast suspension spray and the plasma crossflow by using a three-dimensional two-way coupled Eulerian–Lagrangian model. Here, the suspension consists of ethanol (85 wt.%) and nickel (15 wt.%). Furthermore, at the standoff distance of 40 mm, a flat substrate is placed. To model the turbulence and the droplet breakup, Reynolds Stress Model (RSM) and Kelvin-Helmholtz Rayleigh-Taylor breakup model are used, respectively. Tracking of the fine particles is continued after suspension’s fragmentation and evaporation, until their deposition on the substrate. In addition, the effects of several parameters such as suspension mass flow rate, spray angle, and injector location on the in-flight behavior of droplets/particles as well as the particle velocity and temperature upon impact are investigated. It is shown that the injector location and the spray angle have a significant influence on the droplet/particle in-flight behavior. If the injector is far from the plasma or the spray angle is too wide, the particle temperature and velocity upon impact decrease considerably. Full article
(This article belongs to the Special Issue Trends in Spray Atomization)
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