Response of Stretched Cylindrical Diffusion Flame to Sinusoidal Oscillation of Air Flow Velocity
Response of Stretched Cylindrical Diffusion Flame to Sinusoidal Oscillation of Air Flow Velocity
复制标题
DOI：
10.17265/2159-5275/2017.06.005
复制
发表时间：
2017-06
期刊：
影响因子：
--
通讯作者：
Yosuke Suenaga;H. Yanaoka;M. Kikuchi;S. Sasaki
中科院分区：
文献类型：
--
作者：
Yosuke Suenaga;H. Yanaoka;M. Kikuchi;S. Sasaki
实验研究了具有相对于气流的凸曲率的拉伸圆柱形扩散火焰对周期性气流速度振荡的响应特性。燃料是用氮气稀释的甲烷和氧化剂空气。振荡频率为5 ~ 250hz。结果总结如下：气流速度梯度的波动幅度相对于频率不变，但燃油流的波动幅度增大。火焰半径的波动幅度在5 ~ 25 Hz范围内呈准稳定变化，在大于50 Hz的频率范围内随频率的增加而减小。在相同的速度波动范围内，火焰亮度的振荡幅度小于稳定火焰的振荡幅度。亮度振荡振幅在50 Hz处达到峰值，大于稳定火焰的振幅。认为火焰亮度随频率的复杂变化与火焰厚度与半径之比、空气流和燃料流的速度梯度以及这些值的大小在各自时间变化中的相位差密切相关，其中火焰厚度与半径之比与火焰曲率效应有关，气流速度梯度与火焰拉伸效应有关。以及燃油流的速度梯度对燃油输运的影响。
An experimental study investigated the characteristics of a stretched cylindrical diffusion flame, with a convex curvature with respect to the air stream, in response to periodic air flow velocity oscillation. The fuel was methane diluted with nitrogen, and the oxidizer air. The oscillation frequency was varied from 5 to 250 Hz. The results are summarized as follows. Though the fluctuation amplitude of the air stream velocity gradient was constant with respect to the frequency, the amplitude of the fuel stream increased. The fluctuation amplitude of the flame radius changed quasi-steadily from 5 to 25 Hz, and decreased with increasing frequency in the frequency range greater than 50 Hz. The flame luminosity did not respond quasi-steadily at 5 Hz, and the oscillation amplitude of flame luminosity was less than that of a steady flame, over the same velocity fluctuation range. The oscillation amplitude of luminosity peaked at 50 Hz, and was greater than that of a steady flame. It is considered that this complex change in flame luminosity with respect to frequency was closely related to the phase difference in the respective time variations in the ratio of flame thickness to radius, the velocity gradients of the air and fuel streams, and the magnitude of these values, with the ratio of flame thickness to radius related to the flame curvature effect, the velocity gradient of the air stream correlated to the flame stretch effect, and the velocity gradient of the fuel stream impacting the fuel transportation.