锥形旋流器内燃料分布对模型燃烧室近贫熄状态的影响

Effects of Fuel Distribution of Conical Swirler Dome on Lean Blowout of Model Combustor

关键词:  燃烧室  锥形旋流器  燃料分布  近贫熄  过量空气系数  压力波动

Key words:  Combustor  Conical swirler  Fuel distribution  Near lean blowout  Excess air coefficient  Pressure fluctuation

摘要:

针对近贫熄状态，研究锥形旋流器内燃料分布对模型燃烧室燃烧稳定的影响。在不同空气流量下对头部燃料分布A和B分别进行了锥形旋流器模型燃烧室的贫熄状态实验。结果表明：同样的进气条件下，分布B在贫熄时刻的过量空气系数是分布A的4倍以上，并在可比较的实验流量范围内保持明显的优势；分布B的火焰可以由锥形旋流器外缩入锥形旋流器内熄灭，而分布A的火焰不能缩入旋流器内部，只能在锥形旋流器外部以整团火焰的形态熄灭；锥形旋流器头部中心轴线上引入的少量燃料对燃烧室近贫熄状态的压力脉动有极大影响，分布B的压力波动幅值比分布A降低90%以上，压力波动主频从88Hz减小到50Hz。结合数值模拟计算，从切向涡量角度分析了近贫熄火焰前端稳定在不同位置的原因，比较了两种燃气分布下局部流场物理参数分布的差异，有助于理解与认识锥形旋流器内燃料分布对燃烧稳定性的影响。

Abstract:

Aiming at near lean blowout state, the effects of fuel distribution in conical swirler on combustion stability of a model combustor were studied. Lean blowout experiments on fuel distribution A and B in a conical swirler dome combustor were carried out under different air flow rates. The results show that under the same inlet air conditions, the excess air coefficient of arrange B at lean blowout is more than 4 times that of arrange A, and has obvious advantages in the range of experimental air flow rates. The flame of the arrange B can slowly shrink from the outside into the conical swirler until it is extinguished in the center of the dome, but the flame of the arrange A can only be extinguished outside the conical swirler with the shape of a whole. The amplitude of the pressure fluctuation of arrange B is reduced by more than 90% compared to arrange A, and the main frequency of the pressure fluctuation decreases from 88Hz to 50Hz, which indicates that the gas injected into the dome center greatly inhibits the pressure pulsation in the combustor. Combined with numerical simulation, the reasons why the front end of the flame near lean blowout is stable at different positions are explained from the perspective of azimuthal vorticity, meanwhile, the differences of physical parameters distribution in local stable combustion zones under different gas distributions are compared, which could deepen the understanding of the influence of fuel distribution on combustion stability.