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Design and evaluation of a Laval-type supersonic atomizer for low-pressure gas atomization of molten metals

International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 627-635页

作者： Chao-run Si Xian-jie Zhang Jun-biao Wang Yu-jun Li Shannxi Engineering Research Center for Digital Manufacturing Technology Northwestern Polytechnical University Institute of Applied Mechanics RWTH Aachen University

A Laval-type supersonic gas atomizer was designed for low-pressure gas atomization of molten metals. The principal design ob-jectives were to produce small-particle uniform powders at lower operating pressures by improving the gas inlet and outlet structures and op-timizing structural parameters. A computational fluid flow model was developed to study the flow field characteristics of the designed atom-izer. Simulation results show that the maximum gas velocity in the atomization zone can reach 440 m＆#183;s-1;this value is independent of the atomization gas pressure P0 when P0〉0.7 MPa. When P0=1.1 MPa, the aspiration pressure at the tip of the delivery tube reaches a mini-mum, indicating that the atomizer can attain the best atomization efficiency at a relatively low atomization pressure. In addition, atomization experiments with pure tin at P0=1.0 MPa and with 7055Al alloy at P0=0.8 and 0.4 MPa were conducted to evaluate the atomization capa-bility of the designed atomizer. Nearly spherical powders were obtained with the mass median diameters of 28.6, 43.4, and 63.5μm, respec-tively. Compared with commonly used atomizers, the designed Laval-type atomizer has a better low-pressure gas atomization capability.

关键词： atomizers gas atomization supersonic flow simulation metal powders

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Effects of droplet size and spray interval on root-to-shoot ratio,photosynthesis efficiency,and nutritional quality of aeroponically grown butter head lettuce

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International Journal of Agricultural and Biological Engineering 2022年第1期15卷 79-88页

作者： Mazhar Hussain Tunio Jianmin Gao Waqar Ahmed Qureshi Sher Ali Sheikh Jiedong Chen Farman Ali Chandio Imran Ali Lakhiar Kashif Ali Solangi School of Agricultural Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

The proper selection of the atomizer(droplet size)and nutrient solution spray interval is one of the most important factors to be investigated in aeroponics system for sustainable *** aim of this study was to research the effects of four aeroponics atomizing nozzles(one air-assisted;A_(1),two air-less;A_(2) and A_(3),and one ultrasonic fogger;A_(4))with droplet sizes of 11.24μm,26.35μm,17.38μm,and 4.89μm,respectively,four spray intervals(15 min(I_(1)),30 min(I_(2)),45 min(I_(3))and 60 min(I_(4)))at a 5 min of constant spray time by atomizing the Hoagland’s nutrient solution on growth,root-to-shoot ratio,photosynthesis characteristics,pigments,and nutritional quality of the aeroponically grown *** experimental results demonstrated that in A_(1) atomizer and I_(2) interval,the growth,photosynthesis efficiency,chlorophyll,carotenoids,and nutritional values of the lettuce were significantly higher compared to that grown in A_(2) and A_(3) atomizers at all spray *** shoot developments were more constrained than root,prominent to the alteration of root-to-shoot ratio(fresh and dry)in the influence of different droplet sizes and spray ***,the plants did not grow well in A_(4) atomizer associated with proposed spray *** results disclosed that there was an obvious interaction between droplet sizes(atomizers)and spray intervals for growth,the ratio of root to shoot,photosynthesis efficiency,pigments,and nutritional quality of the aeroponically grown *** research study increases the awareness of the proper droplet size(atomizer)and the regulation of nutrient solution spray interval for leafy vegetables grown in an aeroponics system.

关键词： aeroponics system atomizers droplet sizes photosynthesis efficiency chlorophyll contents quality of lettuce

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Generalized Liquid Film Atomization Theory

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Journal of Thermal Science 2000年第3期9卷 265-270页

作者： HeraldoS.Couto DemetrioBastos－Netto INPE－NationalInstituteForspaceResearch Rod.PresidenteDutrakm40CachoeiraPaulistaSpBrazil12630－000 INPE－NationalInstituteForspaceResearch Rod.PresidenteDutrakm40CachoeiraPaulistaSpBrazil12630－00

The increase of the fuel burning area required by most practical combustion processes in order to guarantee the minimum energy density rate release for their start up and operation is normally achieved by the proper choice among several existing types of atomizers. For instance, impinging and multi-impinging jets atomizers are used in rocket combustion chambers, while splash-plate atomizers find their use when wall film cooling is required. Pressure swirl atomizers, either of simplex or duplex kind, along with Y-Jet or Spider Jet atomizers are used in industrial applications and in turbine combustion chambers. Notice, however, that all the types of atomizing devices listed above have one point in common: they are of pre-filming kind, i.e., before the droplet spray is generated, a liquid film is formed. This liquid film is broken into unstable ligaments which contract under the action of surface tension forming the droplets. Once the film thickness is estimated, the droplets’ SMD (Sauter Mean Diameter) can be calculated, yielding a crucial parameter for the combustion chamber design. However, although this mechanism of droplet formation has been under study for several decades, most of the available results, are based upon experimental data, valid for a special type of atomizer under the given specific conditions only. This work offers a generalized theory for theoretically estimating the SMD of sprays generated by liquid pre-filming atomizers in general.

关键词： atomizers sprays droplets SMD.

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Air Purification Using Mists Generated by an Efficient Multi-fluid Mixer

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Journal of Energy and Power Engineering 2016年第10期10卷 643-649页

作者： Michio Sadatomi Akimaro Kawahara Yutaro Kawasaki Department of Advanced Mechanical Systems Graduate School of Science and Engineering Kumamoto University Kumamoto 860-8555 Japan

Sadatomi and Kawahara developed a special twin-fluid atomizer called a multi-fluid mixer, which can spray mists by supplying air alone because water is automatically sucked by a vacuum pressure arisen inside the mixer. In the present paper, firstly, some applications of the mists sprayed by the atomizer are described. Secondly, the performance of the twin-fluid atomizer with best performance was compared with those of the commercial twin-fluid MMA100 type together with the single-fluid swirl type. In the CO2 adsorption tests, mists were sprayed five minutes by the respective types in turn in a test room, and time variations of CO2 concentration in air after the introduction of CO2 in the room were measured at the bottom of the room to compare the CO2 adsorption rates by the mists for the respective cases. In addition, diameters of droplets for the respective types were measured with a microscope. As a result, superiority of our twin-fluid atomizer was confirmed, because 40% droplets were 20 to 40 μm in diameter, and the CO2 adsorption rate by the mists with our twin-fluid atomizer was 25% higher than that with the commercial ones.

关键词： Air purification mist atomizers CO2 adsorption power.

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