Numerical Study on the Influence of Shaping Air Holes on Atomization Performance in Pneumatic Atomizers

Li, Wentao; Qian, Lijuan; Song, Shaobo; Zhong, Xiaokai

doi:10.3390/coatings9070410

Cited by 18 publications

(15 citation statements)

References 11 publications

(13 reference statements)

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“…Since the TAB model is not intended to model the primary breakup, we have to set up a model that can be used as input to the TAB model. According to reference [18], droplets with an initial diameter of 65 µm were injected into the airflow at the position of the paint hole in this work. In the absence of an accurate model, this assumption is considered accurate.…”

Section: Numerical Computation Parameters and Initial Conditions Settingmentioning

confidence: 99%

Research on Distribution Properties of Coating Film Thickness from Air Spraying Gun-Based on Numerical Simulation

Xie

Wang

2019

Coatings

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This work aims to study the influence of the spraying parameters on the spray flow field and coating thickness distribution during the air spraying process. The shaping air pressure and the target geometry have an important influence on the distribution of coating film thickness. This paper begins with a 3-D physical model of an air spray gun, in which unstructured grids were generated for control domain. A grid independency study was also carried out to determine the optimal number of cells for the simulations. Then the Euler–Lagrange method was used to describe the two-phase spray flow by establishing a paint deposition model. The numerical simulation based on the discrete phase model (DPM) and TAB model has been carried out. A reasonable assumption was proposed based on the analysis of the spraying process, so that the droplets were injected into the airflow at the position of the paint hole. The influence of the shaping air pressure on the air flow field and the coating thickness distribution was analyzed by changing the shaping air pressure. From the numerical simulation results, it can be concluded that the smaller the shaping air pressure, the more concentrated the coating. With increasing the shaping air pressure, the length of the coating film along z-axis gradually increases, the width along x-axis gradually decreases, and the spray area gradually increases. The paper ends with a numerical simulation and experimental study on planar vertical spraying, planar tilted spraying, and cylinder spraying. Comparisons and experiment results verify the validity and practicability of the model built in this paper.

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Section: Numerical Computation Parameters and Initial Conditions Settingmentioning

confidence: 99%

Research on Distribution Properties of Coating Film Thickness from Air Spraying Gun-Based on Numerical Simulation

Xie

Wang

2019

Coatings

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“…It is; therefore, necessary to conduct further research in this area as the description of conical sheets breakup mechanisms is rather scarce in the literature [89]. The measured droplet diameters are mostly much larger compared to different types of atomizers, which produce droplets in the range up to 100-150 µm in diameter, refer to, for example, [58,[90][91][92][93], but in a similar order as compared to fire sprinklers [64,79,94]. Comparing the Sauter mean diameter empirical formulas developed for different atomizers we can also see rather significant differences.…”

Section: Droplet Size Distributionmentioning

confidence: 99%

Experimental Study on Spray Breakup in Turbulent Atomization Using a Spiral Nozzle

2019

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Spiral nozzles are widely used in wet scrubbers to form an appropriate spray pattern to capture the polluting gas/particulate matterwith the highest possible efficiency. Despite this fact, and a fact that it is a nozzle with a very atypical spray pattern (a full cone consisting of three concentric hollow cones), very limited amount of studies have been done so far on characterization of this type of nozzle. This work reports preliminary results on the spray characteristics of a spiral nozzle used for gas absorption processes. First, we experimentally measured the pressure impact footprint of the spray generated. Then effective spray angles were evaluated from the photographs of the spray and using the pressure impact footprint records via Archimedean spiral equation. Using the classical photography, areas of primary and secondary atomization were determined together with the droplet size distribution, which were further approximated using selected distribution functions. Radial and tangential spray velocity of droplets were assessed using the laser Doppler anemometry. The results show atypical behavior compared to different types of nozzles. In the investigated measurement range, the droplet-size distribution showed higher droplet diameters (about 1 mm) compared to, for example, air assisted atomizers. It was similar for the radial velocity, which was conversely lower (max velocity of about 8 m/s) compared to, for example, effervescent atomizers, which can produce droplets with a velocity of tens to hundreds m/s. On the contrary, spray angle ranged from 58° and 111° for the inner small and large cone, respectively, to 152° for the upper cone, and in the measured range was independent of the inlet pressure of liquid at the nozzle orifice.

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“…Only the TAB (Taylor analogy breakup) model is reported to model paint atomization. The TAB model was first used to predict fuel atomization [14,15], and recently, Li et al [16] and Wang et al [17] have applied it to paint an atomization simulation of air sprays. However, the TAB model only considers the secondary atomization and requires empirical initial conditions to solve the model.…”

Section: Introductionmentioning

confidence: 99%

An Atomization Model of Air Spraying Using the Volume-of-Fluid Method and Large Eddy Simulation

Yan

Chen

Chen³

et al. 2021

Coatings

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When painting complex surfaces, such as large-curvature surfaces, poor coating quality is often obtained, which may be caused by lack of an appropriate atomization model, insufficient understanding of atomization mechanisms and laws, and improper painting parameters. This paper presents a numerical model of paint atomization of air spraying using the volume-of-fluid method and large eddy simulation. The interface capture and the turbulent flow were mainly considered in the model: the former was tracked by the volume-of-fluid method and the latter was predicted by the large eddy simulation. After the computational domain being meshed by the staggered-grid method, the governing equations were discretized by the finite volume method and were solved by the SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) Consistent algorithm. The results of numerical simulations show that the characteristics of atomization flow field, such as velocity variation, pressure distribution, and paint volume fraction are in agreement with the regularities of atomization. Moreover, the primary and secondary atomization phenomena can be clearly observed: as soon as the paint issues from the nozzle, the paint flow begins to distort and the paint fragments continuously eject from the main paint flow and then these paint fragments distort and disintegrate into smaller elements. A comparison with the experimental data from the literature proves that the model of the whole atomization process of air spray is effective. The model is suitable for simulating the whole atomization process and easy to obtain initial conditions, which can be applied to set the appropriate painting parameters and study paint atomization mechanisms and laws in depth.

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Numerical Study on the Influence of Shaping Air Holes on Atomization Performance in Pneumatic Atomizers

Cited by 18 publications

References 11 publications

Research on Distribution Properties of Coating Film Thickness from Air Spraying Gun-Based on Numerical Simulation

Research on Distribution Properties of Coating Film Thickness from Air Spraying Gun-Based on Numerical Simulation

Experimental Study on Spray Breakup in Turbulent Atomization Using a Spiral Nozzle

An Atomization Model of Air Spraying Using the Volume-of-Fluid Method and Large Eddy Simulation

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