| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 103 === Self-pressurizing rocket propellants are currently gaining popularity in the propulsion community, especially in hybrid rocket applications. Self-pressurizing oxidizers with its high vapor pressure, can be driven out from the storage tank and injected into combustion chamber without additional complicated pressurization systems. Among the various self-pressurizing oxidizers, nitrous oxide (N2O) is a highly regarded candidate, especially for hybrid rocket applications. In order to effectively atomize the liquid oxidizer, pressure-swirl injector has been widely used. With its inherent high vapor pressure, nitrous oxide spray characteristics in high pressure environments has been an important topics of intensive research interest. However, nitrous oxide is a strong oxidizer and may cause dramatic damage in improper handling. For safety consideration, carbon dioxide (CO2), with identical molecular weight and similar vapor pressure as well as physical and thermodynamic properties is identified as a possible analogous simulant for nitrous oxide (N2O) in order to greatly reduce hazards, environmental impact, and costs. A novel quantitative Planar Laser-Induced Fluorescence (PLIF) method is adapted and developed to characterize the mass distribution of the CO2 spray. A new facility is also developed in this study for the characterization of pressure-swirl injector atomization and vaporization using high speed video photography. A description of the new CO2 Planar Laser-Induced Fluorescence (PLIF) technique and test apparatus is presented in this thesis, along with details of the spray experiments using carbon dioxide as a simulant for nitrous oxide. Preliminary test results suggest that introducing the PLIF method into the cold flow test can successfully reveal the oxidizer mass flow distribution. In other words, this method not only can effectively observe the vaporization process of high vapor pressure fluid, but also can be used to assist the design of nitrous oxide injectors.
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