Shock Tube/Laser Absorption Measurements of Hydroperoxyl Radical Reactions

迫切需要测量与燃烧有关的物质和反应的基本反应速率。我们以高保真度模拟燃烧过程的能力依赖于对控制反应过程的一小部分关键反应的基本反应速率的精确测量。本课题拟测量HO2与CH3、C2H5、HO2、OH反应的高温速率系数。这些反应很难测量，因为反应物的高度反应性质，以及对反应物和产物浓度进行定量和敏感诊断的挑战。这些反应已被确定为燃烧系统中氢氧自由基浓度建模不确定性的主要贡献者。这些反应速率的测量将在高纯度激波管中进行，使用紫外激光吸收OH， HO2， H2O2和CH3自由基和中红外激光吸收H2O。要研究的温度和压力的总体范围是从800到2200k，从0.5 atm到10 atm。这项工作将利用最近获得的可调谐超快（76 MHz）准连续激光系统，随时可以获得广泛的深紫外吸收跃迁和中红外分布式反馈二极管激光器的最新进展。氢氧自由基（HO2）的反应在氢和碳氢化合物的氧化过程中起着重要的作用。我们已经知道的关于这些羟基自由基反应的作用的大部分是来自较低温度（低于800 K）的实验或估计。高温下这些反应的直接实验结果很少（或不存在）或相互矛盾，这对于开发和验证燃烧动力学模型至关重要。还需要开发新的灵敏的物种诊断方法来推进这些研究。更广泛的影响这项研究将提供一个机会，培养新一代的工程科学家在现代燃烧动力学和最先进的激光诊断和激波管技术。这些技术在过去提供了最高质量的高温动力学数据，并将继续成为可靠信息的来源。通过使用当前数据库（斯坦福大学的激波管测量动力学数据库和目前位于伯克利的PrIMe数据仓库）的网络向公众传播这些数据，将为公众、政府工作人员和其他研究人员提供批判性地理解燃烧过程所需的信息。由于燃烧过程中产生的温室气体以及随之而来的全球变暖效应是当今美国人面临的重要问题之一，因此拟议的研究既适当又必要。

0964884Hanson There is a critical need for the measurement of elementary reaction rates for species and reactions relevant to combustion. Our ability to model combustion processes with high fidelity relies on the existence of accurate measurements of fundamental reaction rates of a smaller set of key reactions that control the reaction progress. This project proposes to measure the high-temperature rate coefficients for reactions of HO2 with CH3, C2H5, HO2, and OH. These reactions have been difficult to measure because of both the highly reactive nature of the reactants and the challenges in developing quantitative and sensitive diagnostics for the reactant and product concentrations. These reactions have been identified as major contributors to the uncertainty in the modeling of hydroperoxyl radical concentration in combustion systems. Measurements of these reaction rates will be performed in high-purity shock tubes using UV laser absorption of OH, HO2, H2O2, and CH3 radicals and mid-IR laser absorption of H2O. The overall range of temperature and pressure to be studied is from 800 to 2200 K and from 0.5 atm to 10 atm. This work will take advantage of a recently acquired tunable ultra-fast (76 MHz) quasi-CW laser system for ready access to broad deep-UV absorption transitions and recent advances in distributed feedback diode lasers in the mid-IR.Intellectual MeritReactions involving the hydroperoxyl radical (HO2) play an important role in oxidation pathways of hydrogen and hydrocarbons. Much of what we already know about the role of these hydroperoxyl radical reactions has been derived from lower temperature (below 800 K) experiments, or from estimates. Direct experimental results for these reactions at high temperatures are rare (or non-existent) or contradictory, and are critically needed to enable development and validation of combustion kinetic models. The development of new and sensitive species diagnostics methods are also needed to advance these studies.Broader ImpactThis research will provide an opportunity to train a new generation of engineering scientists in modern combustion kinetics and state-of-the-art laser diagnostic and shock tube techniques. These techniques have provided, in the past, the highest quality high temperature kinetic data available and continue to be a source of reliable information.Public dissemination of this data through the web using current databases (the Kinetic Database Utilizing Shock Tube Measurements at Stanford and the PrIMe data warehouse currently located at Berkeley) will provide the public, government workers, and other researchers with the information needed to critically understand combustion processes. With one of the important problems facing Americans today being the generation of greenhouse gases from combustion processes and the subsequent effect of global warming, the proposed research is both appropriate and needed.