Self-excited circumferential instabilities in a model annular gas turbine combustor: Global flame dynamics
Self-excited circumferential instabilities in a model annular gas turbine combustor: Global flame dynamics
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DOI：
10.1016/j.proci.2012.05.061
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
N. Worth;J. Dawson
中科院分区：
文献类型：
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作者：
N. Worth;J. Dawson
本文介绍了一个模型环形燃气涡轮机燃烧室在强周向自激不稳定性下的整体火焰动力学。燃烧室由12、15或18个湍流预混钝体火焰组成，这些火焰围绕固定圆周的环形布置，从而可以研究火焰分离距离S对全局热释放动力学的影响。减少S被发现产生的谐振频率和极限环振幅的压力和热释放相同的当量比的增加。从上面的高速OH荧光化学发光成像获得的相位平均全球热释放表明，这些变化是由对环形周围火焰结构的大规模修改引起的。对于最大的S研究（12火焰配置）的方位角不稳定性产生了螺旋状的全球热释放结构的每个火焰。当S减小时，相邻火焰之间的大规模合并或连接发生，跨越约一半的环，峰值热释放集中在外部环形壁处。不稳定性的圆周性质从压力测量和相位平均OH电子化学发光中显而易见，显示在环的任一侧上的热释放的相位相隔180°并且以逆时针方向旋转。自旋和站立模式都被发现，但本文只考虑自旋模式。据作者所知，这些是第一次实验，以提供一个相位平均图片的自激方位角不稳定性在实验室规模的环形燃烧室有关的燃气轮机。
In this paper the global flame dynamics of a model annular gas turbine combustor undergoing strong self-excited circumferential instabilities is presented. The combustor consisted of either 12, 15 or 18 turbulent premixed bluff-body flames arranged around an annulus of fixed circumference so that the effect of flame separation distance, S, on the global heat release dynamics could be investigated. Reducing S was found to produce both an increase in the resonant frequency and the limit-cycle amplitudes of pressure and heat release for the same equivalence ratio. The phase-averaged global heat release, obtained from high-speed OH∗chemiluminescence imaging from above, showed that these changes are caused by large-scale modifications to the flame structure around the annulus. For the largest S studied (12 flame configuration) the azimuthal instability produced a helical-like global heat release structure for each flame. When S was decreased, large-scale merging or linking between adjacent flames occurred spanning approximately half of the annulus with the peak heat release concentrated at the outer annular wall. The circumferential nature of the instability was evident from both the pressure measurements and the phase-averaged OH∗chemiluminescence showing the phase of the heat release on either side of the annulus to be ≈180° apart and spinning in the counter clockwise direction. Both spinning and standing modes were found but only spinning modes are considered in this paper. To the best of the authors knowledge, these are the first experiments to provide a phase-averaged picture of self-excited azimuthal instabilities in a laboratory-scale annular combustor relevant to gas turbines.