| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 89 === This research concentrates on the investigation of the spray characteristics of different geometry of the inner structure in pressure swirl atomizers that used in the spray drying system. We compare the characteristics of spray between each atomizer, e.g. the macroscopic properties─ pressure & volume flow rate, flow number, pattern, and spray angle; the microscopic properties─ SMD, standard deviation(σ)of particle size distribution, and to confer atomization in pressure swirl atomizers. The most important is to obtain the standard deviation of particle size distribution by curve fitting, and to confer the change of particle size distribution range. Further, this work tries to investigate that if we can control the concentration of particle size distribution by changing the size and shape of geometry of the inner structure in pressure swirl atomizers.
According to experimentation results, macroscopic properties like volume flow rate and flow number are almost unaffected by the addition of chamfered block, both of them increases with the increasing swirl chamber length (Ls), discharge orifice diameter(do) and the injection pressure differential. In another way, they would also be affected by the manufacturing precision of the chamfered block. Spray angle increases with the increasing discharge orifice diameter(do) and decreases with increasing Ls, and it changes obviously after chamfered block application. On microscopic properties: SMD and σ decreases with increasing pressure difference. Somehow, the existing trends between Ls and SMD change with the application of chamfered block. For σ property, ranges of particle size distribution of small discharge orifice diameter(do=1.2mm) are all less than that of large discharge orifice diameter in any Ls simultaneously indicate that obtained uniform particle size distribution in small do without chamfered block application. Due to the large size of chamfered block compared with the discharge orifice, and also the center deviation trend is unclear in the case of chamfered block application.
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