A monolithic tri-coaxial propellant injection scheme for enhanced mixing of methane-oxygen in liquid-propellant rocket systems is enabled by additive manufacturing. Mixing and combustion characteristics of the tri-coaxial design are assessed experimentally from 1–69 bar using laser absorption tomography and chemiluminescence imaging, and are compared to a traditionally-manufactured bi-coaxial design. Quantitative two-dimensional images of temperature and carbon monoxide mole fraction are generated from the laser absorption spectroscopy methods, while OH* chemiluminescence provides an approximate metric for combustion heat release defining flame length and injector standoff distance. At similar pressures and oxidizer-to-fuel ratios, the tri-coaxial injector design is shown to enhance mixing and combustion progress, reducing characteristic mixing length scales and achieving improved combustion performance relative to more conventional bi-coaxial designs. Despite enhanced mixing, the tri-coaxial design exhibits more limited reduction in flame standoff distance from the injector face, suggesting that increased heat flux to the injector face can be managed. The tri-coaxial injector highlights the potential to leverage additive manufacturing to enhance performance and simplify the fabrication of liquid-propellant rocket engines.

中文翻译：

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增材制造剪切三同轴火箭喷油器混合和燃烧特性


通过增材制造，实现了一种用于增强液体推进剂火箭系统中甲烷-氧混合的整体式三同轴推进剂喷射方案。使用激光吸收断层扫描和化学发光成像在 1-69 bar 范围内对三同轴设计的混合和燃烧特性进行实验评估，并与传统制造的双同轴设计进行比较。温度和一氧化碳摩尔分数的定量二维图像由激光吸收光谱方法生成，而 OH* 化学发光提供了定义火焰长度和喷射器间隔距离的燃烧热释放的近似度量。在相似的压力和氧化炉燃料比下，三同轴喷油器设计被证明可以增强混合和燃烧进度，减少特征混合长度尺度，并相对于更传统的双同轴设计实现更好的燃烧性能。尽管混合增强，但三同轴设计与喷油器表面的火焰对峙距离的减少更加有限，这表明可以管理喷油器表面的热通量增加。三同轴喷油器凸显了利用增材制造提高性能并简化液体推进剂火箭发动机制造的潜力。