A novel fuel regression measurement technique was developed using a single-port, clear polymethylmethacrylate (PMMA) grain and a high-resolution camera, providing temporally and spatially resolved data in a small-scale hybrid motor. By visualizing the fully illuminated port through a flat PMMA surface, the fuel grain diameter can be measured along the axial dimension. This paper provides the details of the implementation, data processing, validation, and results from 21 hotfires. A wide range of operating conditions were tested by varying the initial diameter, the fuel grain length, the oxidizer mass flow rate, and the precombustion chamber length. The main difficulty associated with this technique is correcting the data to account for the change in index of refraction of the solid PMMA as heat soaks into the material surrounding the port. Qualitative and quantitative data can be extracted to further improve our fundamental understanding of hybrid combustion and upgrade motor designs. This new regression method is nonintrusive, low cost, and easy to implement, and it has the potential to provide reliable space–time-dependent data for laboratory-scale motors.

使用单端口透明聚甲基丙烯酸甲酯（PMMA）颗粒和高分辨率相机开发了一种新颖的燃料回归测量技术，可在小型混合动力汽车中提供时间和空间解析数据。通过在平坦的PMMA表面上看到完全照亮的端口，可以沿轴向尺寸测量燃料粒径。本文提供了实施的详细信息，数据处理，验证以及21个热点事件的结果。通过改变初始直径，燃料颗粒长度，氧化剂质量流量和预燃烧室长度，测试了广泛的运行条件。与该技术相关的主要困难是校正数据以解决由于热量浸入端口周围的材料中而导致的固体PMMA折射率的变化。可以提取定性和定量数据，以进一步提高我们对混合燃烧的基本了解并升级电动机设计。这种新的回归方法非侵​​入性，低成本且易于实现，并且有可能为实验室规模的电机提供可靠的时空相关数据。