In this work, two representative hybrid rocket injector designs, a single-port and an axial showerhead design, were examined experimentally to determine the comparative influence on the development of the downstream combustion zone with polymethylmethacrylate (PMMA) fuel. One-dimensional laser absorption tomography was employed to obtain the thermochemical structure of the PMMA–gaseous oxygen reaction layer via quantitative in situ species and temperature measurements. Optical measurements were performed with tunable semiconductor lasers in the midwave infrared to target absorption features in the fundamental vibrational bands of CO, ${\mathrm{CO}}_2$, and ${\mathrm{H}}_2\mathrm{O}$. Planar measurements were conducted at the exit plane of cylindrical fuel grains ($\mathrm{inner}\mathrm{diameter}=0.5\mathrm{in}.$) at axial distances ($x/d$) ranging from 2 to 11 with a constant gaseous oxygen flow for each of the injectors. Assuming azimuthal symmetry, a Tikhonov-regularized Abel inversion technique was used to obtain the radially resolved absorption coefficient, from which temperature and mole fractions were extracted. One-dimensional measurements over all fuel-grain lengths were consolidated to obtain spatially resolved two-dimensional images of the reaction layer thermochemical structure in a hybrid rocket motor geometry. Significant variations in experimental results were observed between the two injectors, suggesting the importance of injection fluid dynamics in hybrid rocket combustion performance. Explanations of the variations are offered from both a theoretical and a computational analysis.

在这项工作中，通过实验检查了两种代表性的混合火箭喷射器设计，即单端口和轴向喷头设计，以确定聚甲基丙烯酸甲酯 (PMMA) 燃料对下游燃烧区发展的比较影响。采用一维激光吸收断层扫描通过定量原位物种和温度测量获得 PMMA-气态氧反应层的热化学结构。使用可调谐半导体激光器在中波红外线中进行光学测量，以针对 CO 基本振动带中的吸收特征，${\mathrm{二氧化碳}}_2$， 和 ${\mathrm{H}}_2\mathrm{哦}$. 在圆柱形燃料颗粒的出口平面进行平面测量（$内\mathrm{直径}=0.5在.$) 在轴向距离 ($X/d$) 范围从 2 到 11，每个注射器都有恒定的气态氧气流量。假设方位角对称，使用吉洪诺夫正则化阿贝尔反演技术获得径向分辨的吸收系数，从中提取温度和摩尔分数。对所有燃料颗粒长度的一维测量进行了合并，以获得混合火箭发动机几何结构中反应层热化学结构的空间分辨二维图像。在两个喷射器之间观察到实验结果的显着变化，表明喷射流体动力学在混合火箭燃烧性能中的重要性。从理论和计算分析中都提供了对变化的解释。