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In this paper, ultrasonic gas atomization (USGA) of Zn–Al under near-zero aspiration pressure was discussed. The protrusion length of delivery tube was modified to adjust the aspiration pressure. Under near-zero aspiration pressure, melt filming was observed by camera and more fine powders were produced. While under larger subambient aspiration pressure, melt filming was unavailable, corresponding to less fine powders. The results suggest that the position of the wake near the delivery tube can be optimized under near-zero aspiration. Less protrusion of delivery tube reduces the energy loss in gas flow deflection. Both facilitate to produce finer powders.

With the rapid development of the air-breathing hypersonic vehicle design, an accurate description of the combustion properties becomes more and more important, where one of the key techniques is the procedure of the liquid fuel mixing, atomizing and burning coupled with the supersonic crossflow in the combustion chamber. The movement and distribution of the liquid fuel droplets in the combustion chamber will influence greatly the combustion properties, as well as the propulsion performance of the ramjet/scramjet engine. In this paper, numerical simulation methods on unstructured hybrid meshes were carried out for liquid spray atomization in supersonic crossflows. The Kelvin-Helmholtz/Rayleigh-Taylor hybrid model was used to simulate the breakup process of the liquid spray in a supersonic crossflow with Mach number 1.94. Various spray properties, including spray penetration height, droplet size distribution, were quantitatively compared with experimental results. In addition, numerical results of the complex shock wave structure induced by the presence of liquid spray were illustrated and discussed.

The global objective of this work is to show the capabilities of the Eulerian–Lagrangian spray atomization (ELSA) model for the simulation of Diesel sprays in cold starting conditions. Our main topic is to focus in the analysis of spray formation and its evolution at low temperature 255 K (-18°C) and nonevaporative conditions. Spray behavior and several macroscopic properties, included the liquid spray penetration, and cone angle are also characterized. This study has been carried out using different ambient temperature and chamber pressure conditions. Additionally, the variations of several technical quantities, as the area coefficient and effective diameter are also studied. The results are compared with the latest experimental results in this field obtained in our institute. In the meantime, we also compare with the normal ambient temperature at 298 K (25°C) where the numerical validation of the model has shown a good agreement.

Particle generation via atomization and spray processes is a widely applied method for powder production. By means of atomization processes, the relevant particle properties may be tailored to the powder user's need in a wide range. Understanding and control of the main subprocesses of atomization is a key feature for choosing a suitable type of spray process and operation conditions. Tailoring particle properties and extending the applications of particle production beyond the current limits is also possible in this way. This contribution highlights some features of spray processes for powder production, namely the gas- and fluid-dynamic processes involved, the materials-related subprocesses, and the formation of the multiphase flow in the spray. As an example, the production of fibre- or sphere-shaped particles from melt atomization is discussed.

Biodiesel has large amount of oxygen in itself, which make it very efficient in reducing exhaust emission by improving combustion inside an engine. But biodiesel has a low temperature flow problem because it has a high viscosity. In this study, the spray behavior and atomization characteristics were investigated to confirm of some effect for the combination of non-esterification biodiesel and fuel additive WDP and IPA. The process of spray was visualized through the visualization system composed of a halogen lamp and high speed camera, and atomization characteristics were investigated through LDPA. When blending WDP and IPA with biodiesel, atomization and spray characteristics were improved. Through this experimental result, SMD of blended fuel, WDP 25% and biodiesel 75%, was 33.9% reduced at distance 6cm from a nozzle tip under injection pressure 30MPa.

This research investigates the performance of an assembly micro-atomizer under single-fluid and twin-fluid operational conditions of micro-encapsulation process. Alginate and CaCl₂ aqueous solution are used as the membrane material and hardening agent, respectively. The high speed images were taken to investigate the formation processes of the microcapsules. Results showed that the formation of the microcapsules depends on the instability modes of the liquid column including asymmetry mode, helical mode, sinusoidal mode and spray developing mode as Reynolds number was increased from 221 to 2210. Excitation at resonance frequency of 2.18 kHz of this system resulted in the production of uniform-sized microcapsules. Moreover, SMD equal to 20 μm can be achieved in low GLR under twin-fluid atomization process. It is not easy to achieve by commercial apparatus.

A pulse combustor employed in a spray drying system offers a new approach for liquid atomization that yields high quality powders at low cost. Using a pulse combustion atomizer, there is no need for any form of nozzle dispersion and its atomization mechanisms differ from those of conventional atomizers, such as rotary atomizers, pressure and pneumatic nozzles. In this work, atomizing experiments, using a Helmholtz-type resonator as atomizer and an optical analyzer for measuring the mean diameters of atomized droplets and their distribution, were carried out and the effects of liquid feed rate, combustion flux oscillating frequency and liquid viscosity on atomized droplet size and size distribution were investigated and analyzed. Results indicate that the droplet-size distribution is similar during conditions with a low feed rate, high frequency pulsating flow, and moderate viscosity. The droplet-size distribution is approximately a normal distribution. The Sauter mean diameter of the droplets ranges from 50 to 80 μm.