Wyniki wyszukiwania - BazTech

1

Numerical estimation of film thickness with an air-assisted spray gun

Baytok Yusuf Mert, Erek Aytunc, Saf Orcun

Engineering Transactions

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2023

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Vol. 71, iss. 2

241--263

EN

The main goal of this study is to present the effects of spraying parameters on the numerical evaluations of the fundamental behaviors of an air-assisted spray gun during the formation of child droplets in the spray flow field and material deposition on the target surface. For this purpose, first of all, the air-assisted spray gun geometry was created using the Solidworks software. Then, a computational domain with a 3D, unstructured grid structure was generated using the ANSYS-Workbench meshing tool. Numerical calculations were conducted using ANSYS-Fluent 2020-R2 commercial software. Different breakup models and their effects on the child droplet size were investigated. By coupling the Taylor analogy breakup (TAB) model and discrete phase model (DPM), the droplet size, trajectory, and coating thickness calculations were made under different atomizing air pressures. Also, the effects of spraying distance and droplet size on coating thickness and the critical Weber (We) number on the atomized particle diameter and particle speed were investigated. The results show that with the increase in atomizing air pressure, droplet sizes decrease and the film thickness on the center of the target surface and droplet speeds increases. Also, increasing the critical Weber number makes it more difficult to atomize the droplets.

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Numerical Simulations of the Effects of Droplet Size and Concentration on Vapour-Droplet JP-10/Air Detonations

Liu L., Zhang Q.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

175--190

EN

Two-dimensional simulations were conducted for JP-10 mono-dispersed vapour-droplet detonation in air, based on the detonation mechanism for clouds and validation of the extending critical droplet size limits in previous tests. In the simulations, the discrete phase model combined with the droplet evaporation and droplet breakup models was used. Utilizing a wide range of mono-dispersed droplet sizes and initial droplet concentrations, all cases of JP-10 droplets with a certain amount of pre-vaporized fuel can successfully achieve the deflagration to detonation transition. Detonation velocities at the equivalent concentration with droplet diameters no larger than 50 μm are in good agreement with the theoretical detonation velocities. The effects of droplet size and initial droplet concentration on the detonation behaviour were also investigated. Detonation velocities attained with droplet diameters below 50 μm appear to decrease very slightly with droplet size, but are almost equal to the velocity in gases. When the droplet diameter is above 50 μm, there is a decrease in simulated detonation velocity compared with fine droplets, and no secondary pressure peak was observed. For fuel-rich combustion, detonation velocities decrease rapidly with an increase in initial droplet concentration, and post-wave pressure fluctuation was obviously irregular, caused by the secondary local explosion of the droplets.

3

Model fazy dyskretnej przepływu powietrza z wykropleniem pary wodnej

Branny M., Nowak B., Ptaszyński B., Kuczera Z., Łuczak R., Życzkowski P.

Górnictwo i Geoinżynieria

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2010

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R. 34, z. 3/1

13-21

PL

W artykule opisano zastosowanie modelu fazy dyskretnej do opisu przepływu powietrza w pionowych szybach wentylacyjnych z kondensacją pary wodnej. Dokonano sprawdzenia warunków, w jakich można stosować model fazy dyskretnej i zaprezentowano wyniki obliczeń dla takich prędkości powietrza w szybach, że przy modelowanych wydatkach masowych monodyspersyjnych strumieni kropel wody, pochodzących z kondensacji, cała woda była wynoszona przez powietrze na powierzchnię.

EN

The paper describes the use of the discrete phase model to describe the movement of air in the vertical ventilation shafts with condensation of water vapor. Conditions under which discrete phase model can be used were verified and the results of performed calculations were presented. The results were obtained fo vertical movement up to the drops of water in the shaft.