中文摘要：

在湍流燃烧大涡模拟的基础上,利用气动声学FW-H方程对甲烷/空气预混火焰的不稳定性进行了数值分析.局部化学当量比的周期性波动,造成燃烧室内出现周期性的压力振荡,随着化学当量比的增大或减小,压力振荡幅值均有所提高;贫氧工况下,压力振荡的频率较低,贫燃工况下,压力振荡频率较高.燃烧室内同时存在周期性的温度振荡和速度脉动;压力振荡与速度脉动趋于同频、同相,而温度振荡在相位上稍有提前.流向涡涡量分布呈现周期性变化趋势,相对而言,贫氧工况下,流向涡涡量较小、涡团尺度较大;贫燃工况下,流向涡涡量较大、涡团尺度较小.

英文摘要：

Based on the large eddy simulation of methane/air premixed combustion,FW-H equation is employed to analyze flame instability.The results reveal that the fluctuations of local equivalence ratio cause cyclical pressure oscillations.Both increasing or decreasing the equivalence ratio lead to the increase in amplitudes of pressure oscillations.The pressure oscillation frequency is low at the equivalence ratio of 1.53,while it remains high at the equivalence ratio of 0.57.Both temperature oscillations and velocity pulsations occur in the combustion chamber.Velocity pulsations and pressure oscillations tend to have the same frequency and phase synchronization,while temperature oscillations are slightly ahead of pressure oscillations in phase.Vorticity magnitudes change periodically.At the equivalence ratio of 1.53,the vorticity magnitudes are low and the sizes of eddy are large.While at the equivalence ratio of 0.57,the vorticity magnitudes are high and the sizes of eddy are small.