Experimental investigation and kinetic modelling of NO formation at elevated pressures using laser diagnostic in a Rapid Compression Machine

减少燃烧过程中的污染物排放是全球面临的主要挑战之一。在这方面，不仅温室气体的总体排放量，而且当地污染物的排放也具有很高的相关性。为了解决这一问题，有必要详细了解燃烧和污染物形成动力学，以便了解其机理并对其进行建模。只有这样，才能制定出相应的对策。因此，本建议旨在用理论和实验相结合的方法来研究一氧化二氮的反应机理。在理论方面，将根据文献资料和本项目产生的数据对动力学模型进行优化。一个特别的重点将是低温反应方案，因为目前可用的模型显示，在这个温度区域内的预测存在很大的分散。在实验方面，在快速压缩机(RCM)中对掺入一氧化二氮的燃料-空气混合物的研究将提供新的信息。除了常规的点火延迟时间测量外，还将在RCM的早期循环燃烧过程中进行一维非侵入式一维NO浓度和温度测量。由于药包中的温度梯度，需要诊断的空间分辨率。因此，提出的诊断是基于自发拉曼散射(SRS)和激光诱导荧光(LIF)。当激光诱导荧光产生高灵敏度的局部NO浓度时，受激拉曼散射将用于测量光衰减和温度。后两个量是量化NO-LIF所需的两个最重要的因素。无LIF和SRS的校准将在RCM中的压缩结束时执行。SRS诊断是基于氮气的。温度将从斯托克斯N_2-受激拉曼散射的谱带形状推断出来，而反斯托克斯N_2-受激拉曼散射将产生非常接近于吸引人的无激光诱导荧光发射波长(~236 nm)的光谱衰减。这种类型的SRS/LIF组合诊断是由LTT的申请者最近开发的，用于高压容器中的汽车燃烧燃料喷射。在目前拟议的项目前半部分，LTT最重要的研究问题将是这种(略有修改的)诊断是否可以应用于RCM中讨论的燃烧过程，以及由此产生的测量不确定度是否至少与以前的工作一样低。我们将研究该诊断在当前环境中的潜力和局限性。在项目的前半部分，将对RCM选定的几种运行条件进行NO-LIF的完全量化。上半场的结果将用于规划下半场，在下半场中，将对各种运行条件进行更多的非LIF测量。

Reducing pollutant emissions in combustion processes is one of the major challenges worldwide. In this context not only the overall greenhouse gas emissions but also the local release of pollutants is of high relevance. For tackling this problem a detailed understanding of the combustion and the pollutant formation kinetics is necessary in order to understand and model its mechanisms. Only by this appropriate counter measures can be developed.As a consequence this proposal aims to investigate the reaction mechanism of nitrous oxide using a combination of theoretical and experimental approach. On the theoretical side kinetic models will be optimized based on literature information and data resulting from this project. A special focus will be on the low temperature reaction scheme since currently available models show a large scatter in the predictions in this temperature regime. On the experimental side investigations of fuel-air mixtures doped with nitrous oxide in a rapid compression machine (RCM) will deliver new information. Besides conventional ignition delay time measurements, one-dimensional quantitative nonintrusive NO concentration and temperature measurements will be conducted in the early-cycle combustion process in the RCM. Spatial resolution of the diagnostic is required because of temperature gradients in the charge. Thus, the proposed diagnostic is based on spontaneous Raman scattering (SRS) and laser-induced fluorescence (LIF). While LIF yields the local NO concentration with high sensitivity, SRS will be applied to measure light attenuation and temperature. These latter quantities are the two most important factors required for quantification of NO-LIF. Calibration of both NO-LIF and SRS will be performed at the end of compression in the RCM. SRS diagnostics are based on nitrogen. The temperature will be inferred from the spectral band shape of Stokes N2-SRS, whereas anti-Stokes N2-SRS will yield attenuation spectrally very close to an attractive NO-LIF emission wavelength (~ 236 nm). This type of combined SRS/LIF diagnostic was recently developed by the applicants at the LTT for automotive combusting fuel jets in a high-pressure vessel. In the currently proposed first half of the project, the most important research question for the LTT will be whether that (slightly modified) diagnostic can be applied to the discussed combustion processes in the RCM and whether the resulting measurement uncertainties are at least as low as in those previous works. The potential and limitations of this diagnostic in the current environment will be investigated. Complete quantification of NO-LIF will be conducted for a few selected operating conditions of the RCM in the first half of the project. The results of that first half will be used for planning the second half, in which a larger number of NO-LIF measurements will be conducted for various operating conditions.