This experimental and theoretical work examines the effects of gaseous oxidizer flow rates and pressure on the regression rates of porous fuels for hybrid rocket applications. Testing was conducted using polyethylene as the porous fuel and both gaseous oxygen and nitrous oxide as the oxidizer. Nominal test articles were tested using 200, 100, 50, and 15 micron fuel pore sizes. Pressures tested ranged from atmospheric to 1160 kPa for the gaseous oxygen tests and from 207 kPa to 1054 kPa for the nitrous oxide tests, and oxidizer injection velocities ranged from 35 m/s to 80 m/s for the gaseous oxygen tests and from 7.5 m/s to 16.8 m/s for the nitrous oxide tests. Regression rates were determined using pretest and posttest length measurements of the solid fuel. Experimental results demonstrated that the regression rate of the porous axial-injection, end-burning hybrid was a function of the chamber pressure, as opposed to the oxidizer mass flux typical in conventional hybrids. Regression rates ranged from approximately 0.75 mm/s at atmospheric pressure to 8.89 mm/s at 1160 kPa for the gaseous oxygen tests and 0.21 mm/s at 207 kPa to 1.44 mm/s at 1054 kPa for the nitrous oxide tests.;The analytical model was developed based on a standard ablative model modified to include oxidizer flow through the grain. The heat transfer from the flame was primarily modeled using an empirically determined flame coefficient that included all heat transfer mechanisms in one term. An exploratory flame model based on the Granular Diffusion Flame model used for solid rocket motors was also adapted for comparison with the empirical flame coefficient. This model was then evaluated quantitatively using the experimental results of the gaseous oxygen tests as well as qualitatively using the experimental results of the nitrous oxide tests. The model showed agreement with the experimental results indicating it has potential for giving insight into the flame structure in this motor configuration. Results from the model suggested that both kinetic and diffusion processes could be relevant to the combustion depending on the chamber pressure.
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机译：这项实验和理论工作研究了混合氧化剂火箭发动机中气态氧化剂流速和压力对多孔燃料回归速率的影响。使用聚乙烯作为多孔燃料，同时使用气态氧和一氧化二氮作为氧化剂进行测试。使用200、100、50和15微米的燃料孔径来测试名义测试物品。气态氧测试的压力范围为大气压至1160 kPa，一氧化二氮测试的压力范围为207 kPa至1054 kPa，气态氧测试的氧化剂注入速度范围为35 m / s至80 m / s，而7.5 m / s至16.8 m / s，用于一氧化二氮测试。使用测试前和测试后对固体燃料的长度测量来确定回归率。实验结果表明，与传统混合器中典型的氧化剂质量通量相比，多孔轴向喷射，端燃烧混合器的回归速率是腔室压力的函数。气态氧测试的回归速率范围从大气压下约0.75 mm / s到1160 kPa时的8.89 mm / s，以及一氧化二氮测试的207 kPa时0.21 mm / s到1054 kPa时的1.44 mm / s。该模型是基于标准烧蚀模型开发的，该标准烧蚀模型经过修改以包括通过谷物的氧化剂流。来自火焰的热传递主要使用经验确定的火焰系数建模，该系数在一项内包含所有热传递机制。还改编了基于颗粒扩散火焰模型的探索性火焰模型，该模型用于固体火箭发动机，用于与经验火焰系数进行比较。然后，使用气态氧测试的实验结果对模型进行定量评估，并使用一氧化二氮测试的实验结果进行定性评估。该模型表明与实验结果吻合，表明该模型具有深入了解这种电动机配置中火焰结构的潜力。该模型的结果表明，取决于燃烧室压力，动力学和扩散过程都可能与燃烧有关。
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