声场频率与振幅对火焰NO_x生成特性的影响

Effects of acoustic frequency and amplitude on NO_x of partially premixed flame

针对频率为0~180Hz和压力振幅为(0~1 000)Pa的声场作用对甲烷/空气部分预混火焰NOx生成特性的影响,通过高速摄像、火焰直拍、热电偶测温等技术,分析火焰EINOx、火焰长度与声场振幅、频率之间的关系.结果显示,在频率为0~180Hz和压力振幅为(1~1 000)Pa内,当频率f一定时,随压力振幅的增加,火焰与周围气体的掺混进一步增强,火焰长度减小,高温区域停留时间减小,致使EINOx生成降低,且EINOx与振幅之间存在线性关系,斜率为-0.009^-0.003.在振幅一定时,随频率的增加,声对火焰的影响逐渐减弱,火焰长度逐渐增加,火焰区域的平均温度降低,导致EINOx增加,且EINOx与频率之间存在线性关系,斜率为0.01~0.03.

Theeffects of acoustic frequency（0~180 Hz） and amplitude（0~1000 Pa） on the NO, of meth- ane/air partially premixed flame wereinvestigated experimentally. High speed camera, flame image and thermocouple temperature measurements were used to analyzethe relationship between acoustic amplitude- and frequencywith EINO,. The results show that whenacoustic amplitude increases, EINO, decreases. Thereason is that under the larger acoustic amplitude, the strengthen of mixing of flame and surrounding gas lead to the decrease of flame length and global residence time, which is the major factorfor the lower EINOx. There is a linear relationship between EINO~ and amplitudethatthe slope of the linear function is range from --0. 009 to --0. 003. The results also show thatwhen acoustic frequency increases, EINO; in- creases. Becausethat under the higher frequency, the effect of acoustic field on flame decreases, then lead tothe longer flame length, which is the reason forhigher EINOx. There is a linear relationship between EINOx and frequencythatthe slope of the linear function is range from 0.01 to 0.03.