基于LES的分层旋流火焰流场结构与火焰响应研究

LES Study on the Flow Field and Flame Response of a Stratified Swirling Flame

本文基于OpenFOAM开展了分层旋流预混火焰的大涡模拟研究。针对独立分层旋流燃烧器(BASIS),采用了不可压缩求解器ReactingFoam,部分搅拌反应器(PaSR)燃烧模型和线性分布的温度边界条件,分别开展了非外激和外激下的大涡模拟。结果表明,非外激下得到的火焰平均结构与实验吻合较好,通过三维流线展示了清晰的旋涡结构;外激条件下,首次获得了该类火焰的火焰传递函数,发现其相位呈线性分布;增益在150 Hz达到极小值,在250 Hz达到极大值,随后在400 Hz后迅速降低,呈现低通滤波器的特征。

In this paper,a Large Eddy Simulation(LES)study of stratified swirl premixed flames is carried out based on OpenFOAM toolbox.For the novel stratified swirl burner(BASIS),the LES was performed with incompressible solver ReactingFoam,Partially Stirred Reactor(PaSR)combustion model and linear-distributed temperature boundary conditions at both the unforced and forced conditions.The results show that the time-averaged flame structure obtained under the unforced condition agrees well with the experimental results.Clear vortex structures are displayed by the three-dimensional streamline.Under the forced conditions,the Flame Transfer Function(FTF)of the stratified flame is obtained for the first time.The phase of FTF is found to be linear relationship with forcing frequency,while the gain firstly reaches the minimum at 150 Hz and then climbs to the maximum at 250 Hz,finally decreases rapidly after 400 Hz,showing a characteristic of the low-pass filter.