火焰增厚燃烧模型计算旋转预混火焰的参数敏感性分析

Large Eddy Simulation of Premixed Swirling Flames with Thickened-Flame Model: a Sensitivity Study

关键词:  大涡模拟  火焰增厚模型  敏感性分析  亚网格燃烧模型

Key words:  Large eddy simulation  Thickened flame model  Sensitivity study  Sub-grid combustion model

摘要:

为了分析各种参数对火焰增厚(TF)模型的影响，并找出各个参数在火焰增厚模型中最佳的适用范围，采用该模型对PRECCINSTA燃烧器内的湍流预混旋转火焰进行了大涡模拟研究，并针对TF模型的主要影响因素:火焰厚度网格数、褶皱函数、动态增厚过程，开展了一系列的敏感性对比计算。研究表明:采用了动态增厚过程的TF计算结果与实验结果的吻合度有明显的提高；如果将层流火焰的厚度增加过大，达到10倍网格尺度，则会对正确预测湍流与火焰的相互作用带来较大困难，对于本文所研究的火焰，火焰厚度网格数的理想范围是2.5 ~ 5.0；采用固定指数的幂律褶皱函数相比于传统的Colin褶皱函数并没有明显的改善。

Abstract:

In order to analyze the effects of each parameter on the thickened-flame (TF) model， and find out the best range of each parameter in the this model， large eddy simulation (LES) of turbulent premixed swirling flames in the PRECCINSTA burner is performed with TF model. A sensitivity study of the model is conducted， for which several factors affecting the performance of TF model are investigated: the flame thickness grid number， the wrinkling function， a dynamic thickening procedure， etc.The investigation shows that the LES results obtained with the dynamic thickening procedure agree better with the experiment data. If the flame front is thickened to 10 times grid size， it becomes difficult for LES to predict the interaction between turbulence and flame correctly. For the flames under consideration in this paper， the ideal range of flame thickness grid number is 2.5 ~ 5. Furthermore， compared to the traditional Colin wrinkling function， the LES results obtained with power law wrinkling function with fixed index do not show a noticeable improvement.