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Development and application of infrared and tracer-based planar laser-induced fluorescence imaging diagnostics.

机译：基于红外和示踪剂的平面激光诱导荧光成像诊断技术的开发和应用。

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摘要

Two different planar laser-induced fluorescence (PLIF) diagnostics have been developed and refined. The first diagnostic, infrared-PLIF for temperature and pressure, utilizes infrared (IR) excitation of small molecules, such as CO, CO2, and H2O, and collection of the subsequent vibrational fluorescence. The second diagnostic, tracer PLIF for simultaneous mole fraction and temperature, utilizes UV excitation and collection of fluorescence from a tracer species (3-pentanone) in the near-UV and visible spectrum.; IR-PLIF measurements of temperature and pressure are a new application of the technique. Initial IR-PLIF measurements focused on species concentrations of CO and CO2. The strong dependence of IR-PLIF signals on temperature and pressure indicated that IR-PLIF measurements of those quantities are possible.; Methods for calculating the absorption cross section and fluorescence quantum yield for infrared laser excitation of small molecules (diatomics and triatomics) are developed to study the temperature and pressure dependence of the fluorescence. An experimental study of IR fluorescence from CO + N 2 mixtures at room temperature conditions is used to evaluate the level of modeling complexity needed to accurately estimate the time-dependent vibrational populations used to calculate the fluorescence quantum yield. A model for the non-local influence of fluorescence radiative trapping is presented and used to estimate the reduction in signal due to trapping as a function of environmental conditions.; Diagnostics for temperature and pressure are developed using the models for absorption cross section, fluorescence quantum yield, and radiative trapping to guide the implementation. A two-line temperature diagnostic capable of measurements in flows with nonuniform pressure and species concentrations is derived from the model results. A slightly altered two-line technique utilizing offset excitation on one of the rotational lines allows for measurements of pressure in flows with nonuniform temperature and species concentrations. Compressible flow fields are an ideal environment for these diagnostics, applied here to imaging an under-expanded jet of CO2 and N2. The demonstration results illustrate the power of these new diagnostics and the feasibility of single-shot measurements of temperature and pressure in compressible flows using IR-PLIF.; The second diagnostic studied, tracer PLIF measurements for simultaneous mole fraction and temperature, involves the selection of a diagnostic for mole fraction measurements and optimization of the diagnostic for use in IC engines. The target of the mole fraction measurements is the distribution of exhaust gas residuals (EGR) present in IC engines. A tracer-based method for measuring EGR is developed using negative-PLIF (N-PLIF) of 3-pentanone seeded into the intake air and fuel of an IC engine.; To eliminate the influence of temperature on the N-PLIF measurements, a simultaneous temperature measurement strategy is selected. An uncertainty analysis is used to select optimal excitation wavelengths for simultaneous imaging of EGR and temperature. The selection process and testing of equipment for the diagnostic is described in detail. Validation of the tracer-based PLIF measurements are performed in an IC engine and measurements under homogeneous in-cylinder conditions are used to tune the 3-pentanone fluorescence quantum yield model and to estimate the accuracy and precision of the optimized diagnostic.; Demonstrations of the diagnostic are performed in an optical IC engine under fired homogeneous-charge compression-ignition (HCCI) operation and under HCCI operation with large negative valve overlap (NVO) and direct injection of fuel during the NVO period. The results validate the ability of the diagnostic to acquire high quality single-shot images of temperature and EGR mole fraction under harsh in-cylinder conditions with highly stratified EGR and temperature distributions. The measurements
机译：已经开发和完善了两种不同的平面激光诱导荧光（PLIF）诊断程序。第一个用于温度和压力的诊断性红外PLIF利用小分子（例如CO，CO2和H2O）的红外（IR）激发，并收集随后的振动荧光。第二个诊断性示踪物PLIF用于同时测定摩尔分数和温度，它利用UV激发和在近紫外和可见光谱中收集示踪物（3-戊酮）中的荧光。 IR-PLIF测量温度和压力是该技术的新应用。最初的IR-PLIF测量着重于CO和CO2的物种浓度。 IR-PLIF信号对温度和压力的强烈依赖性表明，可以对这些量进行IR-PLIF测量。开发了计算小分子（双原子和三原子）的红外激光激发的吸收截面和荧光量子产率的方法，以研究荧光的温度和压力依赖性。在室温条件下，对来自CO + N 2混合物的IR荧光进行实验研究，以评估建模复杂度的水平，该建模复杂度可准确估算用于计算荧光量子产率的随时间变化的振动种群。提出了一种用于荧光辐射捕获的非局部影响的模型，该模型用于估计由于捕获而引起的信号减少与环境条件的关系。使用吸收截面，荧光量子产率和辐射捕获模型来开发温度和压力诊断程序，以指导实施。从模型结果中得出了两线温度诊断程序，该诊断程序能够测量压力和物质浓度不均匀的流量。一种稍微改变的两线技术，在一根旋转线上利用偏移激励，可以测量温度和物质浓度不均匀的流中的压力。可压缩的流场是这些诊断的理想环境，此处可用于对二氧化碳和氮气的膨胀不足的射流进行成像。演示结果说明了这些新诊断方法的强大功能以及使用IR-PLIF一次性测量可压缩流中的温度和压力的可行性。研究的第二种诊断方法是同时进行摩尔分数和温度的示踪剂PLIF测量，包括选择用于摩尔分数测量的诊断剂和优化用于IC发动机的诊断剂。摩尔分数测量的目标是IC发动机中存在的废气残留物（EGR）的分布。利用3-戊酮的负PLIF（N-PLIF）播种到内燃机的进气和燃料中，开发了一种基于示踪剂的EGR测量方法。为了消除温度对N-PLIF测量的影响，选择了同步温度测量策略。不确定性分析用于选择最佳激发波长，以便同时对EGR和温度成像。详细介绍了诊断设备的选择过程和测试。基于示踪剂的PLIF测量在IC引擎中进行验证，并且在均质缸内条件下进行测量以调整3-戊酮荧光量子产率模型并估算优化诊断的准确性和精确度。诊断的演示是在光学IC发动机中进行的均质充气压缩点火（HCCI）操作下，以及在HCCI操作下具有较大的负气门重叠（NVO）和在NVO期间直接喷射燃料的情况下进行的。结果证实了诊断工具能够在苛刻的缸内条件下以高度分层的EGR和温度分布获取高质量的温度和EGR摩尔分数的单次图像的能力。测量

著录项

  • 作者

    Rothamer, David A.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 318 p.
  • 总页数 318
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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