Experiments and modeling of the breakup mechanisms of an attenuating liquid sheet

Asgarian, Ali; Heinrich, Martin; Schwarze, Rüdiger; Bussmann, Markus; Chattopadhyay, Kinnor

doi:10.1016/j.ijmultiphaseflow.2020.103347

Cited by 27 publications

(9 citation statements)

References 21 publications

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“…Perforations arise randomly on the sheet of the water discharged from the standard flat-fan nozzle, 28,29 and it is hypothesized that they are produced by the modulation of sheet thickness induced by surface disturbance. 30 It is not clear whether surface disturbance is the main factor underlying the generation of perforations on the spray sheet of an air-induction nozzle.…”

Section: Resultsmentioning

confidence: 99%

Visualization of the evolution of bubbles in the spray sheet discharged from the air‐induction nozzle

Gong

Kang

2022

Pest Management Science

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BACKGROUND The air‐induction nozzle greatly reduces drift potential by increasing spray droplet size compared with a standard flat‐fan nozzle. The current study aims to reveal the mechanism behind the formation of large droplets through the air‐induction nozzle from the aspect of bubble evolution in the spray sheet. RESULTS Bubble break‐up leads directly to the formation of perforations because large bubbles reach both sides of the spray sheet. The surface disturbance induced by bubble break‐up modulates spray sheet thickness, which indirectly leads to the generation of perforations. Compared with the spray pressure, nozzle configuration has a more significant effect on both the volumetric flow rate of intake air and the thickness of the spray sheet. As the nozzle is changed from ID‐120‐01 to ID‐120‐05, the volumetric flow rate of intake air increases by 801.30% at a spray pressure of 0.3 MPa, whereas spray sheet thickness increases by 412.50% at a radial distance of 10 mm. CONCLUSION Bubble break‐up is the main reason for the generation of perforations within an air‐induction nozzle, leading to early break‐up of the spray sheet and the production of large spray droplets. Bubble break‐up can be effectively controlled by modifying the nozzle configuration.

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Section: Resultsmentioning

confidence: 99%

Visualization of the evolution of bubbles in the spray sheet discharged from the air‐induction nozzle

Gong

Kang

2022

Pest Management Science

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“…Therefore, the sheet of the oil‐based emulsion spray has a relatively thicker thickness as it breaks up. As a result, the spray droplets generated by the thicker spray sheet have relatively larger sizes 23 . However, some experimental results indicate that this tendency is not suitable for the air‐induction spray.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the spray droplets generated by the thicker spray sheet have relatively larger sizes. 23 However, some experimental results indicate that this tendency is not suitable for the air-induction spray. In these cases, relative to the water spray, the oil-based emulsion spray has a short sheet length 24 but small volumetric median diameter of droplets.…”

Section: Introductionmentioning

confidence: 99%

Effect of oil‐based emulsion on air bubbles in the spray sheet produced through the air‐induction nozzle

Gong

Kang

2022

Pest Management Science

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BACKGROUND: The air-induction spray featured by air bubbles involved in the spray sheet has attracted great attention in applications of agricultural spray due to its advantages of alleviating spray drift and promoting deposition. The objective of the presented study is to deepen the understanding of the mechanism of the air-induction spray through elucidating the effect of sprayed liquid on characteristics of air bubbles in the spray sheet. RESULTS:The air bubbles with relatively large sizes are stable for a long time span. As velocity of the water spray increases from 6.85 m s −1 to 17.87 m s −1 , average size of the air bubbles decreases from 383.21 ∼m to 236.47 ∼m. With the introduction of organosilicone surfactant, the surface tension of the sprayed liquid decreases from 67.38 mN m −1 to 31.32 mN m −1 ; accordingly, average size of the bubbles decreases from 383.21 ∼m to 160.9 ∼m. Compared to aqueous solutions spray, the oil-based emulsion spray is responsible for relatively small average size of air bubbles as the surface tension and spray velocity are respectively similar. CONCLUSION: Low drainage rate of the bubble lamella contributes to high stability of large air bubbles. The decrease of the average size of air bubbles is responsible for small volumetric median diameter of oil-based emulsion spray compared with water spray. Besides the increase of the spray velocity and the decrease of the surface tension, the Marangoni effect caused by dynamics of oil droplets at air-liquid interface also contributes to the decrease of average size of air bubbles.

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“…Different from the cylindrical liquid jet, the fat-fan spray has a complex geometry that makes it difficult to find simplified assumptions ( Lefebvre, 1989 ). Nonetheless, there have been some attempts to establish a theoretical model to describe the atomization process and forecast the droplet size of the flat-fan spray ( Kashani et al., 2018 ; Asgarian et al., 2020 ). For water spray, the most common theoretical model is termed the “wave model”, which was first proposed by Fraser et al.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental studies on the oil-based emulsion spray

2023

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Oil-based emulsion is a common herbicide formulation in agricultural spray, and its atomization mechanism is different from that of water spray. In this paper, a theoretical model based on the characteristics of spray sheets was proposed to predict the spray droplet size for oil-based emulsion spray. An image processing method was used to measure droplet size distributions for different spray pressures and nozzle configurations, and the measured results were used to validate the theoretical model. The results show that oil-based emulsion spray is characterized by the web structure constituted by perforations. The liquid originally occupied by spray sheets eventually gathers in these web structures. The proposed theoretical model is based on the size of the nozzle exit, the angle of spray sheets, and the perforation number in the web structure, which are relatively easy to obtain. The theoretical droplet size is in inverse proportion to the square root of the perforation number in the web structure while in proportion to the square root of the area of the nozzle exit. The captured images of spray sheets and the measured droplet size distribution show consistency with the theoretical prediction. The difference between theoretical results and measured volumetric median diameter is less than 10% for different spray pressures and nozzles.

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Experiments and modeling of the breakup mechanisms of an attenuating liquid sheet

Cited by 27 publications

References 21 publications

Visualization of the evolution of bubbles in the spray sheet discharged from the air‐induction nozzle

Visualization of the evolution of bubbles in the spray sheet discharged from the air‐induction nozzle

Effect of oil‐based emulsion on air bubbles in the spray sheet produced through the air‐induction nozzle

Theoretical and experimental studies on the oil-based emulsion spray

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