伴流速度和当量比对部分预混火焰闪烁频率的影响

Effects of Co-flow Velocity and Equivalence Ratio on the Flickering Frequency of Partially Premixed Flames

在不同空气伴流速度和燃料当量比的条件下,对甲烷/空气部分预混射流火焰闪烁进行了直接数值模拟(DNS),分析了伴流速度和燃料当量比对火焰闪烁频率的影响.数值模拟结果表明:伴流能够有效地抑制火焰的闪烁行为.存在1个临界伴流速度比(Ucr),当伴流速度比小于Ucr时,随着伴流速度比的增加,火焰锋面周围的涡旋尺度变小,火焰闪烁频率增加;当伴流速度比大于Ucr时,火焰的闪烁行为完全消失.燃料当量比增加,火焰锋面周围的涡旋尺度变大,火焰闪烁频率减小.

The flicker of partially premixed methane/air jet flames was studied using direct numerical simulation( DNS)under various co-flow velocities and equivalence ratios,and the effects of co-flow velocity and equivalence ratio on the flickering frequency of flames were analyzed. The results show that co-flow can effectively suppress the flicker of flames.A critical co-flow velocity ratio(Ucr)existed. When the co-flow velocity ratio was less than Ucr,the vortex scale around the flame front will decrease and the flickering frequency will increase with the growing co-flow velocity ratio;when the co-flow velocity ratio was greater than Ucr,the flicker of flames will completely disappear.In addition,the vortex scale around the flame front will become larger and the flickering frequency will decrease with the growing equivalence ratio.