The Development of Sensitive Diagnostics and Their Use in Shock Tube Studies of Formaldehyde and Formyl Reaction Rate Coefficients

项目概述这是一个两部分的研究计划，包括一个新的可调谐紫外激光吸收诊断的发展和应用这种诊断甲醛氧化和氮氧化物动力学的调查。 利用230 nm附近的强紫外吸收特性，利用环形染料激光器和外部倍频器，研制了一种灵敏的甲酰基（HCO）吸收诊断系统。 这种方法应产生三倍增加的HCO的灵敏度超过目前的激光吸收测量在614 nm。还使用了先前开发的在306 nm处的灵敏（ppm级）羟基（OH）激光吸收诊断和在174 nm处的甲醛（CH 2 O）灯吸收诊断。 羟基是燃烧系统中自由基池发展的重要标志，该程序将能够更好地分离复杂CH 2 O/HCO/O2动力学系统中的某些反应。这些诊断允许测量以下反应在大约温度范围1000至1600 K：HCO + O2？CO + HO2 （a）HCO + NO？CO + HNO（B）CH 2 O + O2？HCO + HO2 （c）CH2O + OH？HCO + H2O（d）涉及甲醛（CH 2 O）和甲酰基自由基（HCO）的反应位于甲烷和其他烃类燃料的主要氧化途径。 即使有了这个主要作用，在这个子机制中的许多关键反应的高温速率系数仍然存在很大的不确定性。 这些反应速率的实验测量中的不确定性主要源于不能以足够的灵敏度测量重要的反应物质，例如HCO，并且不能从干扰反应中动力学地分离各个反应。更高的灵敏度测量HCO结合使用的补充诊断OH允许设计更简单，更直接的实验，更少的干扰反应，因此能够更可靠地确定几个重要的基本反应的速率系数。更广泛的影响这项工作有助于显着的研究生教育和科学数据库和影响燃烧化学建模活动在政府实验室和行业。 该计划为研究生提供了一个学习最先进的激光和激波管方法的机会，并在世界一流的实验室获得实践经验。 在这个程序中开发的实验技术包括在研究生实验室课程和教科书。 在该计划中获得的数据，结果和专业知识积极与政府和行业共享，特别是通过基于网络的动力学数据库的开发和分发，燃烧相关反应速率的审查以及个人联系。

PROJECT SUMMARYThis is a two-part research program consisting of the development of a new tunable ultraviolet-laser absorption diagnostic and the application of this diagnostic to the investigation of formaldehyde oxidation and nitrogen-oxide kinetics. A sensitive formyl (HCO) absorption diagnostic using a ring-dye laser with an external frequency doubler is developed that takes advantage of the strong ultraviolet (UV) HCO absorption feature near 230 nm. This method should yield a threefold increase in HCO sensitivity over the current laser absorption measurements made at 614 nm. Also used are a sensitive (ppm level) hydroxyl (OH) laser absorption diagnostic at 306 nm and a formaldehyde (CH2O) lamp absorption diagnostic at 174 nm that have been developed previously. Hydroxyl is an important marker of radical pool development in combustion systems and this procedure will enable better isolation of certain reactions in the complex CH2O/HCO/O2 kinetic system. These diagnostics permit measurement of the following reactions over the approximate temperature range 1000 to 1600 K:HCO + O2 ? CO + HO2 (a)HCO + NO ? CO + HNO (b)CH2O + O2 ? HCO + HO2 (c)CH2O + OH ? HCO + H2O (d)Reactions involving formaldehyde (CH2O) and formyl radical (HCO) lie on the primary oxidation pathway for methane and other hydrocarbon fuels. Even with this primary role, there are still large uncertainties in the high-temperature rate coefficients of many of the key reactions in this sub-mechanism. The uncertainty in the experimental measurements of these reaction rates stems largely from an inability to measure important reaction species, such as HCO, with sufficient sensitivity and to kinetically isolate the individual reactions from interfering reactions. Higher-sensitivity measurements of HCO combined with the use of complementary diagnostics for OH permit the design of simpler, more direct experiments with fewer interfering reactions, and hence enable more reliable determinations of rate coefficients for several important elementary reactions.Broader impactThis work contributes significantly to graduate education and scientific databases and impacts combustion-chemistry modeling activities in government laboratories and industry. The program provides an opportunity for graduate students to learn state-of-the-art laser and shock-tube methods and gain practical experience in a world-class laboratory. Experimental techniques developed in this program are included in graduate laboratory classes and textbooks. Data, results and expertise acquired in this program are actively shared with government and industry, particularly through the development and distribution of web-based kinetics databases, reviews of combustion-related reaction rates, and personal contacts.