Hencken火焰结构对FS-CARS光谱温度定标影响的研究

发布时间：2018-12-21 10:53

【摘要】：在燃烧场中,温度是最为重要的参数,如何准确且快速的获取温度信息具有重要的实际意义,可以为建立有效的燃烧模型、深入地了解燃烧的物理和化学过程以及改进现有的燃烧系统提供重要的参考。在燃烧测温领域,测温方式分为热电偶等接触式测量及CARS等激光光谱非接触测量手段。其中,接触式测量易受环境条件限制,且不适用于高温测量;激光光谱非接触式测量不受测温环境条件的限制,且能实现对高温领域高度的时间和空间分辨。本课题即利用非接触式测温中的飞秒单脉冲CARS光谱技术研究Hencken火焰结构对其温度定标拟合过程的影响。本文先对Hencken型燃烧器和CARS光谱技术的研究现状进行介绍;对丙烷/空气的平焰扩散火焰特征进行定性研究;以及用热电偶测温方法对燃烧场的轴向及不同横截面的温度分布规律进行研究;其次,用飞秒单脉冲CARS光谱技术对Hencken燃烧器燃烧场中的一维温度分布进行测温研究,并分析该Hencken燃烧器不同测点温度与理论CARS光谱最佳拟合温度的拟合误差。根据以上研究思路,设计了符合实验所需的Hencken型平焰燃烧器,搭建了S型热电偶测温装置,研究了不同当量比、平均流速、氧气浓度等因素对温度分布的影响规律。实验结果表明,火焰呈近正四棱锥形,火焰的高度及燃尽情况主要取决于燃料的流量,且当量比为0.471时,随着轴向高度的增加,测点温度近正弦曲线般波动而后逐渐降低,平均的降温幅度为0.5℃/mm,整个轴向高度方向的所有测点的温度平均值为1131℃,比理论计算温度低1.4%,即该工况测温结果和理论计算温度最接近;随着甲烷流量的升高,轴向温度随高度的升高逐渐呈现出先减小再增大后降低的现象,整体呈现波动变化的规律;当氧气浓度为21%时,在测量范围内,轴向温度随着高度的增加基本无变化。同时,搭建了一套基于啁啾脉冲的飞秒单脉冲CARS光谱实验装置,以Hencken燃烧器产生的高温火焰为探测样品。实验结果表明,利用飞秒CPP-CARS光谱技术对火焰温度一维分布的测量,测量温度在1350K和1450K之间,和热电偶测量的结果较为符合,而且可以看出从火焰的一侧到另一侧火焰温度呈现现增大后减小的趋势,在火焰中心温度最高;且与所测得的CARS光谱进行拟合的理论CARS光谱的最佳模型参数基本无变化,拟合误差主要集中在0.01和0.02附近。
[Abstract]:In the combustion field, temperature is the most important parameter. How to obtain the temperature information accurately and quickly has important practical significance, which can be used to establish an effective combustion model. An in-depth understanding of the physical and chemical processes of combustion and the improvement of existing combustion systems provide important references. In the field of combustion temperature measurement, the temperature measurement can be divided into thermocouple contact measurement and laser spectrum non-contact measurement such as CARS. The contact measurement is easy to be restricted by the environmental conditions and is not suitable for high temperature measurement. The laser spectrum non-contact measurement is not limited by the environmental conditions of the temperature measurement and can realize the time and space resolution of the height of the high temperature field. In this paper, femtosecond monopulse CARS spectroscopy in non-contact temperature measurement is used to study the effect of Hencken flame structure on the fitting process of temperature calibration. In this paper, the research status of Hencken burner and CARS spectroscopic technology is introduced, and the characteristics of flat flame diffusion flame of propane / air are studied qualitatively. The temperature distribution of combustion field in axial direction and different cross section is studied by thermocouple method. Secondly, the one-dimensional temperature distribution in the combustion field of Hencken burner is studied by femtosecond monopulse CARS spectroscopy, and the fitting error between the temperature of different measuring points of the Hencken burner and the optimum fitting temperature of theoretical CARS spectrum is analyzed. According to the above research ideas, the Hencken type flat flame burner is designed, and the S type thermocouple temperature measuring device is built. The influence of different equivalent ratio, average flow rate and oxygen concentration on the temperature distribution is studied. The experimental results show that the flame is nearly quadrilateral, the height and burnout of the flame mainly depend on the flow rate of the fuel, and the equivalent ratio is 0.471. With the increase of the axial height, the temperature of the measuring point fluctuates like a sinusoidal curve and then decreases gradually. The average temperature of all the measuring points in the direction of the whole axial height of 0.5 鈩，

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