The present study was conducted in order to clarify the effects of airflow turbulence on the spray combustion. Methanol was atomized with the two-fluid-type nozzle in order to generate the spray flame, and the turbulence characteristic of the flame was varied by inserting a mesh near the tip of the nozzle. Droplets in the spray flame were measured using a PDPA system in a reaction field, and changes in the turbulence characteristic were measured using a hot-wire anemometer in a no-reaction field in order to clarify the effects of turbulence on combustion behavior. Inserting a finer mesh promoted droplet evaporation and enhanced the dispersion characteristic. Regarding changes in the turbulence characteristic, the integral time scale increased and the energy spectrum decreased as the inserted mesh became finer. Based on the obtained results, we determined that a finer mesh causes vortexes to be more persistent and enhances the dispersion characteristic of the droplets.

The authors investigated the effect of the turbulence of an air current on droplet dispersion in a spray flame. Wire meshes of different mesh sizes were inserted behind a two-fluid type nozzle each time to vary the air current turbulence characteristics, and then methanol was sprayed to form a spray flame. Droplets in the spray flame were measured with a Phase Doppler Particle Analyzer (PDPA). In the no-reaction field, the turbulence characteristics were measured by using a hot wire anemometer to determine the influences of the turbulence on droplet dispersion in a flame. As the mesh size of the wire mesh was reduced in the investigation, the droplet dispersion was shown to reduce the volume of cluster and also the number density of the droplets. Measuring the turbulence statistics confirmed a decrease of the Stokes number in proportion to the mesh size of the wire mesh. Droplet flying trajectories through turbulence were calculated. According to the calculation results, inserting a finer wire mesh was found to move flying trajectories closer to the streamline of the vortex. When a finer wire mesh was inserted, droplets were drawn closer to the vortex and formed clusters near the vortex. Consequently, droplets were found to disintegrate and disperse under the great influences of a vortex.

The interfacial phenomena of magnetic fluids subjected to a normal magnetic field are studied experimentally. To begin with, the effect of the shape and the dimension of the transparent containers on the interfacial phenomena is examined for two kinds of magnetic fluids, ferricolloid W-40 and ferricolloid HC-50. The cross-sectional shape of the container is made to be circular, square and hexagon. The dimension of the container is set to 55 mm, 70 mm and 85 mm. The critical magnetic induction values B c calculated on the basis of the present expriment are compared with those obtained from the theoretical analysis by Cowley & Rosensweig, where at these values of B c the interfacial phenomena begin to be built up. Finally, on the hysteresis in generating the transition between three kinds of deformation modes on the interface, the present observation results are compared with those obtained from the analysis by A. Gailitis. It was concluded that the shape and the dimension of the containers had no effect on the interfacial phenomena, and the critical value B c caluculated by measured data agreed with that of the theoretical analysis. And also, the mechanism of the hysteresis was clarified mathematically in the manner of the analysis by Gailits.

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