基于K赫兹甲醛PLF测量研究分析火焰几何结构和燃烧不稳定性的耦合

2018/12/07   下载量： 0 次

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应用领域 能源/新能源
检测样本 其他
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参考标准 暂无

采用4千赫兹重复频率的Nd:YAG激光器的紫外355nm输出，对气体燃料燃烧火焰的外部几何形态，形貌随时间的变化及其和燃烧不稳定性的关系进行了测量，记录和分析。得到了许多重要的规律。

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In the past, flame geometry was found to play an important role in determining when strong pressure
fluctuations associated with a combustion instability occur in a gas turbine model combustor. The goals of
this study were to use flame surface area as a more accurate way to quantify the flame shape and the heat
release rate, in lieu of chemiluminescence; to accurately resolve both the spatial structure and the time history
of the heat release fluctuations, and to show that kilohertz formaldehyde planar laser-induced fluorescence
provides a new way to achieve these goals. The dual-swirl burner, developed at DLR Stuttgart by
Meier et al. was operated using dimethyl ether (DME) to study fluctuations in the flame surface area, flame
brush, flame length, and heat release rate. To understand the instability, accurate measurements are needed
of the correlation between heat release rate fluctuations and pressure fluctuations. Thus heat release rate
must be recorded as a function of time and space. However conventional chemiluminescence offers only
a line-of-sight measurement. High-speed CH2O PLIF was applied to study the motion of flame surfaces
in response to the pressure oscillations. Results show that the flame surface density fluctuated at the acoustic
frequency (typically 320 Hz). The frequency of the combustion instability was found to increase as
either the gas velocity or the flame speed was increased. These trends are consistent with previous n-s theories
that model the convective time delay. Strong pressure oscillations occur for conditions when the flame
is nearly flat; the instability disappears when the flame becomes V-shaped. The explanation is that all points
on a flatter flame have the same convective time delay but this is not true for the V-flame geometry.

上一篇 在一个双稳湍流涡旋火焰中，对间歇性动态的时间-频率定位
下一篇 抖盒子（‘Shake The Box’):一种利用粒子位置预判方法的高效精确的层析粒子跟踪测速（Tomo-PTV）方法。

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北京欧兰科技发展有限公司
金牌会员 丨 第17年
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