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Structure of a Laminar Premixed Flame with Spatially Non-uniform Stretch Rate

具有空间不均匀拉伸率的层流预混火焰的结构

基本信息

批准号：
14550194
负责人：
MIZOMOTO Masahiko
金额：
$ 2.43万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550194/
关键词：
Combustion Premixed Flame Flame temperature Flame Stretch Lewis Number Heat Transfer PIV Thermocouple 熱の移動

项目摘要

To gain further understanding of turbulent combustion, I investigated experimentally the structures of a laminar premixed flame with spatially non-uniform stretch effect. A flame surface with stretch rate variation was formed by creating a wrinkled laminar premixed flame in a spatially periodic flow field of a lean propane/air mixture, and the relation between flame stretch and flame temperature was discussed from the velocity and temperature distributions. The velocity or temperature was measured using PIV or thermocouple, respectively.The measured flame temperature was lower/higher than the adiabatic flame temperature at flame segments with positive/negative stretch rates. This was a result of flame stretch and Lewis number effect for Lewis number greater than unity. The flame temperature estimated using the conventional theory of flame stretch and Lewis number effect, which is based on a uniform stretch rate along the flame surface, did not agree quantitatively with the measured temperature. Therefore, I revised the theory, taking into account heat transfers along the flame surface and toward the burned gas, and then produced estimates that agreed quantitatively with the measured temperature. I found that flame stretch and Lewis number effect is changed along the flame surface which has spatially stretch rate variation, causing a temperature gradients along the surface and toward the burned gas, which in turn transfer heat and change the flame temperature. Thus, such heat transfers are important factors in estimating flame temperature. In addition, it is clarified that the heat transfer along the flame surface affects more than that toward the burned gas.

为了进一步了解湍流燃烧，本文对具有空间非均匀拉伸效应的层流预混火焰结构进行了实验研究。在周期性流场中，以贫丙烷/空气混合物为对象，通过产生褶皱层流预混火焰，形成了拉伸率变化的火焰面，并从速度和温度分布的角度讨论了火焰拉伸与火焰温度的关系。分别用PIV和热电偶测量了火焰的速度和温度，在正、负拉伸率的火焰段，测量的火焰温度低于/高于绝热火焰温度。这是火焰拉伸和刘易斯数效应的结果，因为刘易斯数大于1。传统的火焰拉伸理论和刘易斯数效应是基于火焰表面沿着的均匀拉伸率，用这种理论估算的火焰温度与测量的温度在数量上不一致。因此，我修改了该理论，考虑到沿着火焰表面和向燃烧气体的热传递，然后得出与测量温度定量一致的估计值。发现火焰拉伸和刘易斯数效应沿沿着火焰面发生变化，火焰面在空间上具有拉伸率的变化，导致沿火焰面沿着向燃烧气体方向的温度梯度，进而传递热量，改变火焰温度。因此，这种热传递是估计火焰温度的重要因素。此外，它是澄清，热传递沿着火焰表面的影响比对燃烧气体。