喷嘴间距对贫油熄火特性和流场结构的影响

Effects of nozzle spacing on lean blowout performance and flow fields

为深入认识喷嘴间距对燃气轮机燃烧室贫油熄火和气动性能的影响,基于典型的双旋流扩散燃烧喷嘴设计了喷嘴位置连续变化可调的双头部模型燃烧室。实验测量了不同初始当量比条件下喷嘴间的最大传焰距离,分析了火焰传播的动态过程;此外还研究了喷嘴间距对贫油熄火当量比、反应流场和方均根速度场的影响。实验结果表明:当量比每增加0.1,无量纲最大联焰间距增大0.2左右,并且喷嘴间的联焰过程大致可分为四个阶段;单喷嘴的贫油熄火当量比大于任意喷嘴间距下双喷嘴的贫油熄火当量比;随着喷嘴间距的减小,贫油熄火当量比先减小后增大;另外,喷嘴间距减小导致射流合并,气流径向速度抵消变小,中心射流速度峰值增大以及回流区尺寸缩小;随着喷嘴彼此靠近,喷嘴间的方均根速度变大,分布区域变广。

In order to deepen understanding of the influence of nozzle spacing on lean blowout and aerodynamic performance of gas turbine combustor,a dual-head model combustor with continuously adjustable nozzle position was designed based on the typical dual-stage swirling diffusion nozzles.The maximum flame propagation spacing between nozzles was measured and the dynamic process of flame propagation was analyzed with different initial equivalent ratios.Additionally,the effects of nozzle spacing on the lean blowout equivalent ratio,reacting flow field and root mean square velocity field were studied.The experimental results show that:with the increase of the equivalent ratio of 0.1,the dimensionless maximum flame propagation spacing increases by about 0.2,and the flame propagation process between nozzles can be roughly divided into four stages.The lean blowout equivalent ratio of single nozzle is bigger than that of double nozzles with arbitrary nozzle spacing.As the double nozzles spacing decreases,the lean blowout equivalent ratio first decreases and then increases.In addition,the decrease of nozzle spacing leads to jet mergence,decrease of radial velocity,increase of central jet velocity peak and decrease of size of central recirculation zone.As the nozzles move close to each other,the value and distribution area of root mean square velocity between nozzles become larger and wider.