Performance Improvement of Swirl Type Micro Bubble Generator (Atomizing Effect by Swirl Chamber Outlet Shape with Taper)

Abstract

Recently, the micro bubble with bubble diameter of less than 50μm is paid to attention. As for this micro bubble, various characteristics that bubble with diameter of several mm doesn’t have are possessed. For instance, water purification, oil separating, growth promotion of creature, and reduction of frictional resistance are reported. The swirl type method, the pressurizing dissolution method, and the perforated plate method, etc. are proposed as the method for generation of micro bubble. The swirl type method can comparatively generate the micro bubble even by low-pressure power in simple structure. In this present study, the effect of shape of swirl chamber on bubble diameter was examined by using the three kinds of shape of swirl type micro bubble generators, which were cylindrical type, taper type, and improved taper type. As a result, it was found to be able to reduce the bubble diameter in the order of improved taper type, taper type, and cylindrical type. And it was clarified that radial outflow type generator could make bubble diameter small compared with axial outflow type generator, and the optimum nozzle shape was the nozzle with inlet angle of 45 degrees, outlet angle of 60 degrees, and nozzle diameter of 3mm. Moreover, it was found that the average bubble diameter of 30μm was obtained under pressure condition of 0.22MPaG in the above-mentioned nozzle shape.