Numerical studies of vortex shedding in forced oscillatory non-premixed flames
Numerical studies of vortex shedding in forced oscillatory non-premixed flames
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DOI：
10.1088/1757-899x/10/1/012030
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发表时间：
2010-06
期刊：
影响因子：
--
通讯作者：
Xi Jiang
中科院分区：
文献类型：
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作者：
Xi Jiang
采用高精度数值方法对甲烷非预混射流火焰的流动不稳定性及其相互作用进行了对比研究。通过比较全三维情况和理想轴对称情况，研究了射流扑动模式和浮力不稳定性之间的相互作用，以确定三维效应对涡动力学的影响。此外，还对空气同向流火焰进行了数值模拟，研究了剪切不稳定性和浮力不稳定性之间的相互作用。有人发现，三维效果占主导地位的火焰动力学在下游位置，火焰表现出过渡行为。轴对称模拟仅能够捕获靠近喷嘴出口的流动动力学。空气同向流动倾向于稳定火焰并减少火焰不稳定性，这也可能对闪烁频率产生影响。三维效应可以极大地影响下游位置处的火焰振荡能量的强度，其中扑动模式增强火焰不稳定性。相反，并流会降低火焰振荡的强度，特别是在上游位置。
A comparative study has been performed to nvestigate the flow nstabilities and their nteractions n a non-premixed methane jet flame using highly accurate numerical methods. The nteraction between the jet flapping modes and buoyancy nstability has been examined by comparing a full three-dimensional case and an idealised axisymmetric case, in order to identify the three-dimensional effects on the vortex dynamics. In addition, air co-flow flames have been numericaly simulated to nvestigate the interaction between the shear and buoyancy nstabilities. It was found that three-dimensional effects dominate the flame dynamics at downstream locations, where the flame exhibits transitional behaviour. The axisymmetric simulation is only able to capture the flow dynamics close to the jet nozzle exit. The air co-flow tends to stabilise the flame and to reduce the flame unsteadiness, which may also have an mpact on the flickering frequency. Three-dimensional effects can greatly affect the strength of flame oscillation energy at downstream locations, where the flapping modes enhance the flame unsteadiness. On the contrary, co-flow tends to reduce the strength of flame oscillation, especialy at upstream locations.