Assumed PDF modeling of turbulent spray combustion
Assumed PDF modeling of turbulent spray combustion
复制标题
DOI：
10.1080/00102200008947336
复制
发表时间：
2000-01-01
影响因子：
1.9
通讯作者：
Borghi, R
中科院分区：
文献类型：
--
作者：
Demoulin, FX;Borghi, R
本研究是尝试将气体湍流燃烧建模方法扩展到喷雾湍流燃烧的新步骤。我们的注意力集中在由喷雾产生的新的随机波动上。这里发展的思想是基于Borghi（1995）提出的讨论。对方程的局部研究使我们能够在混合分数方差方程中找到由喷雾蒸发引起的新相关项的闭合。这是在没有新的假设的情况下完成的，只是通过使用KIVA II代码中已经开发的随机方法来描述喷雾蒸发。我们还展示了一个新变量Z(i)的重要性，它描述了蒸发流体颗粒的初始状态。该变量的PDF及其平均值的方程也以封闭形式写成。目前，它对混合分数PDF的贡献是通过其平均值来考虑的。最后，我们用一个实验验证了我们的模型，其中一组实验条件接近无限快化学，另一组实验条件证明了有限化学动力学的影响。我们发现实测数据和计算结果在定性上是一致的。应该做进一步的发展，例如，将该模型与雾化模型相结合，以避免对蒸发和燃烧过程的第一阶段进行任何假设。
The present study is a new step in the attempt to extend an approach used in the modeling of gaseous turbulent combustion to spray turbulent combustion. Our attention is focused on the new random fluctuations created by the presence of the spray. The ideas developed here are based on the discussion presented by Borghi (1995). A local study of the equations allows us to, find a closure for the new correlation term induced by spray evaporation in the equation for the variance of the mixture Fraction. This was done without new assumptions, just by using the stochastic approach already developed in the KIVA II code to describe spray vaporization. We also show the importance of a new variable, Z(i), which describes the initial state of an evaporated fluid particle. An equation for the PDF of this variable and for its mean value is also written in closed form. For the moment, its contribution to the mixture fraction PDF is taken into account through its average value. Finally we have tested our model with an experiment where one set of experimental conditions is close to the infinitely fast chemistry and another set of conditions demonstrates the effect of finite chemical kinetics. We have found a qualitative agreement between the measured data and our computational results. Further development should be done, for instance coupling this model with an atomization model to avoid any assumption about the first stages of the evaporation and combustion process.