Recent advances in physical understanding and quantitative prediction of impinging-jet dynamics and atomization

Chen, Xiao; Yang, Vigor

doi:10.1016/j.cja.2018.10.010

Cited by 37 publications

(6 citation statements)

References 55 publications

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“…Coughing, which can generate droplets and droplet nuclei, is a typical symptom of COVID-19. These virion-laden respiratory fluid droplets are expelled into the environment by powerful airflow during coughing ( Scharfman et al , 2016 ; Chen and Yang, 2019 ). Measuring the air velocity, droplet number density, velocity, and size distribution is critical to understanding and modeling virus transmission.…”

Section: Introductionmentioning

confidence: 99%

The motion of respiratory droplets produced by coughing

Wang

Zhang

et al. 2020

Physics of Fluids

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Coronavirus disease 2019 has become a global pandemic infectious respiratory disease with high mortality and infectiousness. This paper investigates respiratory droplet transmission, which is critical to understanding, modeling, and controlling epidemics. In the present work, we implemented flow visualization, particle image velocimetry, and particle shadow tracking velocimetry to measure the velocity of the airflow and droplets involved in coughing and then constructed a physical model considering the evaporation effect to predict the motion of droplets under different weather conditions. The experimental results indicate that the convection velocity of cough airflow presents the relationship t −0.7 with time; hence, the distance from the cougher increases by t 0.3 in the range of our measurement domain. Substituting these experimental results into the physical model reveals that small droplets (initial diameter D ≤ 100 μ m) evaporate to droplet nuclei and that large droplets with D ≥ 500 μ m and an initial velocity u 0 ≥ 5 m/s travel more than 2 m. Winter conditions of low temperature and high relative humidity can cause more droplets to settle to the ground, which may be a possible driver of a second pandemic wave in the autumn and winter seasons.

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Section: Introductionmentioning

confidence: 99%

The motion of respiratory droplets produced by coughing

Wang

Zhang

et al. 2020

Physics of Fluids

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“…In rocket engines 7 and aero engines, 8 the sprays are induced to collide to fully mix the fuel with the oxidizer, which plays an important role in combustion performance and engine emission. 9 The injection pressure is relatively low, and the spray collision is a continuously steady process.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the effect of various collision angles and critical conditions on marine engine’s twin-spray collision process

Xia

Zhang

Wang

et al. 2022

International Journal of Engine Research

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To enhance the fuel-gas mixing and phase transition process, the fuel is injected by twin injectors in a large-bore low-speed two-stroke marine engine, while the cylinder condition has reached the transcritical and supercritical conditions. The twin-injector configuration has a great potential for further optimization, but the exploration on the outcome of collision and phase transition was still limited. Therefore, this work aims to study the effect of various collision angles (60°, 90°, 120°, 150°) and critical conditions (sub/trans/supercritical) on the twin-spray collision process using optical techniques. A wide range of experimental cases are conducted to provide an analysis and database for future modeling validation. The post-collisional spray structures, spatial distribution, and periphery features are analyzed to characterize the droplet’s collision. The results show that with the collision angle increasing, the higher collision velocity enhances the mass transfer while the minor vertical component results in a smaller axial dispersion. Because of the trade-off relationship between the vertical velocity component and pre-collision penetration, a higher reduction in droplet momentum results in a slighter collision behavior. At the collision angle of 150°, the subcritical condition tends to result in an off-axis collision. Under the transcritical (P) condition, the probability of head-on collision increases and presents a wider spatial distribution. But under the supercritical condition, because of the existence of the liquid collision, the thermal conversion among phases is accelerated, while the ambient resistance is reduced. Moreover, an exponential correlation of collision liquid length is formulated to predict the axial dispersion based on various critical conditions.

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“…Utilizing th nology derived from microchip production [5,6,9], the inlet, outlet, and filter chann prevent nozzle clogging are etched into the silicon wafer, enabling the componen largely and precisely produced [10]. Components of Respimat ® SMI Inhaler and mechanism of atomization [11].…”

Section: Introductionmentioning

confidence: 99%

“…Based on the VOF method, this paper n ically simulated the jet flow and atomization of the Uniblock atomization chip Inlet and outlet channels of the Uniblock are designed to produce high amounts of fine particles (droplet diameters <5.8 µm) that rely on the physical principles of impinging jet dynamics and atomization. Xiaodong Chen et al [11] have verified the action mode of the double impinging jet by high-fidelity simulation combined with experiments. The impinging jets will initially form a liquid sheet.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigation on Key Parameters of the Respimat® Spray Inhaler

Tong

et al. 2020

Processes

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Respimat®Soft MistTM is a newly developed spray inhaler. Different from traditional nebulizers, metered-dose inhalers, and dry powder inhalers, this new type of inhaler can produce aerosols with long duration, relatively slow speed, and a high content of fine particles. Investigating the effect of the key geometric parameters of the device on the atomization is of great significance for generic product development and inhaler optimization. In this paper, a laser high-speed camera experimental platform is built, and important parameters such as the geometric pattern and particle size distribution of the Respimat®Soft MistTM are measured. Computational fluid dynamics (CFD) and the volume of fluid method coupled with the Shear Stress Transport (SST) k-ω turbulence model are applied to simulate the key geometric parameters of the device. The effects of geometric parameters on the spray velocity distribution and geometric pattern are obtained. The angle of flow collision, the sphere size of the central divider and the length and width of the flow channel show significant impacts on the spray atomization.

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Recent advances in physical understanding and quantitative prediction of impinging-jet dynamics and atomization

Cited by 37 publications

References 55 publications

The motion of respiratory droplets produced by coughing

The motion of respiratory droplets produced by coughing

Experimental study of the effect of various collision angles and critical conditions on marine engine’s twin-spray collision process

Numerical and Experimental Investigation on Key Parameters of the Respimat® Spray Inhaler

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