旋流管状火焰在声场激励下的响应特性研究

Experiment on dynamic response characteristics of tubular flame excited by acoustic field

实验研究了甲烷/空气预混旋流管状火焰在声场信号激励下的动态响应特性,获得了混合气体不同空气流量下火焰对声场激励信号频率的动态响应范围,揭示了声场激励下管状火焰的稳定燃烧范围及火焰结构、压力波动、热释放率的周期性变化规律。结果表明,火焰对声场激励信号的动态响应呈现低通滤波性,转捩频率约为195 Hz。声场信号激励频率大于195 Hz后火焰响应弱化,激励频率越大对火焰影响越小,相同激励频率下空气流量越大对火焰影响越小;声场激励信号小于195 Hz时火焰响应多样化,当空气体流量大于标准状态下100 L/min后火焰在声场作用下直接熄灭,空气体流量小于标准状态下100 L/min则存在火焰轴向振荡燃烧的声场信号激励频率区间,在此区间内火焰表现为与激励频率同频的受迫振荡燃烧。

The dynamic response of methane/air premixed swirling tubular flame under the excitation of acoustic field signal was investigated,and the dynamic response range of flame to the frequency of acoustic field excitation signal was obtained under different air flow rates of gas mixture,which revealed the stable combustion range of tubular flame and the periodic changes of flame structure,pressure fluctuation and heat release rate under the excitation of acoustic field.The results show that the dynamic response of the flame to the acoustic field excitation signal is low-pass filtered,and the turning frequency is about 195 Hz.The flame response weakens when the excitation frequency of the acoustic field signal is greater than 195 Hz,and the larger the excitation frequency is,the smaller the influence on the flame.In addition,the larger the air flow rate is at the same excitation frequency,the smaller the influence on the flame.The flame response is diversified when the acoustic field excitation signal is less than 195 Hz.When the air flow rate is greater than 100 L/min,the flame directly extinguishes because of the acoustic field.When air body flow is less than 1oo L/min,there is a flame axial oscillation combustion of the acoustic field signal excitation frequency interval,and in this interval the flame exhibits forced oscillation combustion with the excitation frequency.