Atomization improvement of high-speed liquid jet with wall impingement and its utilization

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The purpose of the present study is to clarify the possible improvement effect of liquid atomization of wall impingement of a high-speed liquid jet. It was revealed that farming a liquid film with wall impingement has a great effect of improvement of liquid atomization in a high-speed liquid jet. In contrast to a flee jet, in such wall impingement atomization, even the nozzle diameter can be a parameter to control the mean droplet diameter, since with the increase in the nozzle diameter the mean diameter is slightly deed. The minimum mean diameter obtained in the technique of wall impingement of a liquid jet was 17 um. The benefit to utilize the wall impingement was increased with the decrease of the injection pressure. At the liquid injection pressure of 0.5 Mpa which was the lowest value tested in the present study, the mean diameter goes to 45 um while that for free jet was 700 um. This means that the atomization improvement effect can be 1/16 for the wall impingement liquid jet. In … More the initial stage of the present study, a combined effect with the application of a micro-nozzle array and a piezo-electric element were expected. However it was shown that they do not have any favorable effect of the improvement of liquid atomization.In the application to a fuel atomizer in jet engines, more realistic experimental rendition close to a real jet engine was established by applying a large capacity of liquid pump. A laser light scattering technique was also applied to evaluate the spatial spray distribution with the cross-sectional spray imaging. Results showed that the mean diameter does not depend on the air velocity but decreases almost linearly with the increase in the liquid injection velocity. The minimum mean diameter obtained goes to 17 um. The average concentration of spray varies almost linearly with the mass flow rates of air and the liquid. Thus the spatial distribution of the spray was also successfully evaluated as well as the atomization behavior and useful suggestion could be obtained in proceeding to the stage of combustion. Furthermore due to the needs to measure smaller droplet size a liquid nitrogen freezing method was developed utilizing a specially designed probe and a digital microscope. Less