混合时间对燃烧稳定性影响的实验研究

Experimental Investigation of the Effect of Mixing Time on Combustion Stabilities

燃烧振荡是不稳定燃烧过程与燃烧室内声波耦合产生的一种现象,在燃气轮机的贫预混燃烧室中较为常见,其发生易损坏燃烧室结构及缩短运行寿命。本文通过模型燃烧室进行系列实验研究燃料与空气的混合时间对旋流预混燃烧稳定性的影响规律。实验中通过改变预混长度和空气流速来改变混合时间,通过变当量比获得燃烧振荡与稳定的范围。实验结果表明混合时间对燃烧稳定性有重要影响,仅当混合时间处于一定区间内时才有可能发生燃烧振荡,发生燃烧振荡的当量比范围也与混合时间有关。本文同时还研究了燃烧振荡频率、振幅与当量比和空气流速的关系。

Combustion oscillation is a coupling phenomenon of unsteady combustion and acoustic waves in combustors, which is common in lean premixed combustors of gas turbines. The occurrence of combustion oscillation can do harm to combustor structures and shorten their operation lifetime. In this paper, the effect of fuel-air mixing time on stabilization of swirling premixed combustion was investigated through a series of experiments conducted in a model combustor. In experiments, mixing time was changed by variable premixing lengths and airflow velocities. Experiments with different equivalence ratios were conducted to obtain the ranges of combustion oscillation and stable combustion. Experimental results indicate that mixing time of fuel and air has significant effect on combustion stabilization. Combustion oscillation can only occur when mixing time is in some ranges. The range of equivalence ratio in which combustion oscillation can occur is also related to mixing time. The influence of equivalence ratio and airflow velocity on frequency and amplitude of combustion oscillation was also studied in this Paper.