The Role of HO2 and RO2 Radicals in Preignition Reaction Chemistry

为了减少排放和燃料消耗，下一代地面运输发动机预计将在采用低温燃烧（LTC）的循环上运行。 然而，在LTC的基本化学动力学和限速步骤尚未直接探讨，因为无法测量的关键化学成分，氢过氧（HO 2）和烷基过氧（RO 2）自由基，控制的过程。 在这项研究中，一种新的激光吸收诊断相结合的两个更传统的技术将被用来克服这个测量问题，并允许直接测量这些过氧自由基在预点火条件下，与发展的基本理解的基础化学的目标。 新的诊断，腔增强磁光旋转（CEMOR），结合了腔增强衰荡光谱，它提供了测量自由基和磁光旋转的灵敏度，提供了必要的选择性，以消除干扰，从其他化合物具有类似的吸收特性。 这项工作将有助于下一代发动机系统的设计，提高效率和减少排放。 这项工作的更广泛影响将包括培训学生燃烧科学和最先进的光学诊断技术。在这项工作中收集的数据将提供必要的信息，以进一步了解燃烧化学，其在产生温室气体中的作用，以及对气候变化的后续影响。 将努力加强少数民族学生的招收和参与研究和研究生教育。 外展活动包括NSF的RET和REU现场计划。

1335760CernanskyIn an effort to reduce emissions and fuel consumption, next generation ground transportation engines are expected to operate on cycles that employ Low Temperature Combustion (LTC). However, the underlying chemical kinetics and rate limiting steps in LTC have not been directly explored because of an inability to measure the key chemical constituents, hydroperoxy (HO2) and alkylperoxy (RO2) radicals, that control the process. In this study, a new laser absorption diagnostic combining two more traditional techniques will be employed to overcome this measurement problem and allow direct measurement of these peroxy radicals at preignition conditions, with the goal of developing a fundamental understanding of the underlying chemistry. The new diagnostic, cavity enhanced magneto-optical rotation (CEMOR), combines cavity enhanced ringdown spectroscopy which provides the sensitivity to measure the radicals and magneto-optic rotation which provides the selectivity necessary to eliminate interference from other compounds with similar absorption characteristics. This work will aid in the design of the next generation engine systems with increased efficiency and reduced emissions. The broader impact of the work will include training students in combustion science and state-of-the-art optical diagnostics techniques. The data collected in this effort will provide necessary information to further understand combustion chemistry, its role in the generation of greenhouse gases, and the subsequent effect on climate change. Efforts will be made to enhance minority student recruitment and participation in research and graduate education. Outreach activities include NSF's RET and REU site programs.