本篇研究是以直徑10 mm水旋風分離器為例，探討並研發一直徑30 mm新型同軸溢流管水旋風分離器，提升分級效率以及增加多重分級的效果。本研究以碳酸鈣與聚甲基丙烯酸甲酯做為實驗物料，利用Fluent套裝軟體做流場內模擬及分析，模擬流體之速度分佈、壓降分佈、動能分佈以及粒子軌跡。確認模擬及實驗的偏差值，再利用套裝軟體進行新型水旋風分離器的模擬與設計。 模擬過程中設計多種不同長度組合的溢流管，包含同軸溢流管內短外長設計、同軸溢流管內長外短設計以及同軸底流管的設計。另外更比較不同長度溢流管組合以及單雙進料口比較。 實驗結果顯示使用粒徑範圍較廣的碳酸鈣粒子越能代表模擬的可靠性；同軸溢流管使用內短外長的設計可以讓粒子透過二次渦流再次進行分離，使物料可在分離出不同粒徑範圍；在底流部分增加一實心圓柱可以使之取代空氣柱，使流體可以更加穩定沿著實心圓柱往溢流管部分流動；內長外短的同軸溢流管經過模擬後，結果顯示內管長為17.5 mm以及外管長為52.5 mm可以得到最佳的分離效果。 This study took a 10 mm hydrocyclone as an example. We researched and development a 30 mm hydrocyclone with concentric vortex finder. The purpose was to improve the partial separation efficiency and have the effect of multiple classification. The CaCO3 and PMMA was as our material. A numerical software, Fluent, was used for analyzing the distributions of fluid velocity, static pressure, kinetic or the particle tracks. Then use the Fluent to design a new type of hydrocyclone. There were variety of different combinations of overflow pipe in the simulation. Such as the concentric vortex finder which includes the inside pipe is short when the outside pipe is long. The opposite is also true. On the other hand, we compared the single inlet with the double inlet on the hydrocyclone. The simulation results showed that when the size distribution rage of material is large as CaCO3 can improve the reliability with the experimental. If the outside overflow pipe is longer than the inside overflow pipe, it could make the particle separate again with the secondary vortex. The air core could be replaced when we installed a solid cylinder in the cone of hydrocyclone. The result showed that the length of inside overflow pipe and outside overflow pipe are 17.5 mm and 52.5 mm is the best design.