Modelling of instabilities in turbulent swirling flames
Modelling of instabilities in turbulent swirling flames
复制标题
DOI：
10.1016/j.fuel.2009.06.024
复制
发表时间：
2010
期刊：
影响因子：
7.4
通讯作者：
K. Dinesh;K. Jenkins;M. Kirkpatrick;W. Malalasekera
中科院分区：
文献类型：
--
作者：
K. Dinesh;K. Jenkins;M. Kirkpatrick;W. Malalasekera
本文采用大涡模拟方法研究了湍流非预混旋流火焰的不稳定性。被称为SM火焰的所选火焰基于悉尼旋流燃烧器实验数据库。连续性、动量和混合分数的控制方程在结构化的笛卡尔网格上求解，Smagorinsky涡粘性模型和动力学过程被用作亚网格尺度湍流模型。热化学变量采用定常层流火焰面模型描述。结果表明，大涡模拟成功地预测了上游海崖体形成的第一回流区和下游旋流形成的第二回流区。总的来说，LES与测量值的比较是一致的。产生的功率谱和快照表明中心射流和回流区的振荡。火焰SM1的快照显示中心射流的不规则进动，并且位于两个回流区之间的下游轴向位置处的功率谱显示出不同的进动频率。定义为循环膨胀和崩溃的回流区的模式II不稳定性也被确定为火焰SM2。涡动、化学反应和放热的耦合作用表现为Ⅱ型不稳定性。所提出的模拟表明的效率和适用性的LES技术旋流火焰。
A large eddy simulation-based data analysis procedure is used to explore the instabilities in turbulent non-premixed swirling flames. The selected flames known as SM flames are based on the Sydney swirl burner experimental database. The governing equations for continuity, momentum and mixture fraction are solved on a structured Cartesian grid and the Smagorinsky eddy viscosity model with dynamic procedure is used as the sub-grid scale turbulence model. The thermo-chemical variables are described using the steady laminar flamelet model. The results show that the LES successfully predicts the upstream first recirculation zone generated by the bluff body and the downstream second recirculation zone induced by swirl. Overall, LES comparisons with measurements are in good agreement. Generated power spectra and snapshots demonstrate oscillations of the centre jet and the recirculation zone. Snapshots of flame SM1 showed irregular precession of the centre jet and the power spectrum at a downstream axial location situated between the two recirculation zones showed distinct precession frequency. Mode II instability defined as cyclic expansion and collapse of the recirculation zone is also identified for the flame SM2. The coupling of swirl, chemical reactions and heat release exhibits Mode II instability. The presented simulations demonstrate the efficiency and applicability of the LES technique to swirl flames.