主燃级旋流数影响三级旋流燃烧室流动与燃烧特性试验

Experiment on effect of main swirl number on the flow and combustion characteristics of three-stage swirl combustor

为了研究主燃级旋流数对三级旋流燃烧室内的流动、燃烧特性,设计了两种不同主燃级旋流数的旋流器,通过粒子图像测速仪(PIV)与火焰自发辐射手段得到了燃烧室的流场和火焰结构。研究结果表明:主燃级旋流数的改变对出口流动以及点熄火极限油气比影响较大,主燃级旋流数增加使回流涡心位置向中心和上游靠近,中心回流区高度增加,出口涡量强度降低,下游中心回流区内侧的回流速度,湍流强度增加,火焰结构对称,成功点火时间减少,主燃级旋流数为0.8的点火极限油气比较主燃级旋流数为0.7在进口流量为200、250、300、350 m^(3)/h各工况对应增加了48%、41%、26%、24%,熄火极限油气比各工况均增加30%以上。燃烧时,火焰呈一定的"V"型张角向外燃烧。点火时,火焰沿着中心回流区边界向内侧发展。

To study the effect of main swirl number on the flow and combustion characteristics of three-stage swirl combustor, two different main swirl number swirlers were designed. The flow field and flame structure were obtained with particle image velocimetry(PIV) and flame spontaneous emission. Results showed that the change of main swirl number had a great influence on the outlet flow, the lean ignition fuel air ratio and the lean blowout fuel-air ratio. With the increase of the main swirl number, the position of the vortex core was close to the center and upstream location. The height of the center toroidal recirculation zone was increased, while the vorticity of the outflow was decreased. The recirculation velocity and turbulence intensity inside the center toroidal recirculation zone were increased, and the flame structure was symmetrical. The successful ignition time was reduced. Compared with primary stage swirl number 0.7, the lean ignition fuel-air ratio of primary stage swirl number 0.8 was increased by 48%, 41%, 26%, and 24% at volume flow rate of 200, 250, 300,350 m^(3)/h, respectively. Besides, the lean blowout fuel air ratio was increased by more than 30% in each operating condition. During the combustion process, the flame burned outward at a certain "V" opening angle. During the ignition process, the flame developed to the inner side along the boundary of the center toroidal recirculation zone.