Investigation of Turbulent Flame Propagation Mechanism and Development of Turbulent Combustion Model

为了建立适用于具有层流燃烧速度等多种燃烧特性的多种燃料在高压下的通用湍流燃烧模型，对氢、甲烷、丙烷等气体燃料和异辛烷等液体燃料的层流和湍流燃烧进行了研究。在0.10 ~ 0.50MPa下，得到了这些燃料的贫至富混合物的层流燃烧速度、马克斯坦数和湍流燃烧速度。发现湍流燃烧速度与未拉伸层流燃烧速度之比与湍流雷诺数、湍流强度与未拉伸层流燃烧速度之比以及Markstein数有关。在这三个主导因素中，湍流雷诺数和Markstein数被简化为湍流雷诺数和Lewis数组合的一个因素，即湍流雷诺数除以Lewis数的平方。毕竟，我们发现不同压力下的湍流燃烧速度与湍流强度与未拉伸层流燃烧速度之比这两个参数以及湍流雷诺数除以刘易斯数的平方有关。除上述结果外，还发现恒定Peclet数下的湍流燃烧速度与Karlovitz数相关。在本研究的所有结果中，发现热扩散效应影响湍流火焰。最后，用火焰半径表示了爆炸过程中湍流燃烧速度的变化。公式中的系数取决于湍流雷诺数、湍流强度与未拉伸层流燃烧速度之比以及马克斯坦数。

In order to develop universal turbulent combustion model applicable at elevated pressures for a lot of fuels having various combustion properties such as laminar burning velocity, laminar and turbulent combustion was studied for gaseous fuels of hydrogen, methane, propane, and liquid fuel of iso-octane. Laminar burning velocities, Markstein numbers and turbulent burning velocities were obtained for lean to rich mixtures of these fuels at 0.10 to 0.50MPa.The ratio of turbulent burning velocity to unstretched laminar burning velocity was found to depend on the turbulence Reynolds number, the ratio of turbulence intensity to unstretched laminar burning velocity, and the Markstein number. Among these three dominant factors, the turbulence Reynolds number and the Markstein number were reduced to one factor of the combination of the turbulence Reynolds and Lewis numbers, the turbulence Reynolds number divided by the square of the Lewis number. After all, turbulent burning velocities at various pressures were found to correlate with two parameters of the ratio of turbulence intensity to unstretched laminar burning velocity, and the turbulence Reynolds number divided by the square of the Lewis number. In addition to the above results, turbulent burning velocity at a constant Peclet number was found to correlate with the Karlovitz number. In all results in this study, thermo-diffusive effects were found to affect turbulent flames.Finally, variations of turbulent burning velocity during explosions were formulated in terms of flame radius. The coefficient in the formulation was found to depend on the turbulence Reynolds number, the ratio of turbulence intensity to unstretched laminar burning velocity, and the Markstein number.