基于数值方法的燃气轮机贫预混旋流燃烧室单头部结构设计

Design of Dome Structure for A Lean Premixed Swirled Combustor of Gas Turbine Based on the Numerical Method

为分析贫预混旋流燃烧室头部结构特性影响,采用计算流体力学方法研究了中心体端面形状、空气流量,燃料喷孔数量、位置,以及头部扩张比对燃烧火焰、流场及火焰动态响应的影响。结果表明:空气流速增大到一定值后,火焰形态基本保持不变;增加压力面燃料孔数量,高放热率区集中在中心回流区根部,同时增加压力面和吸力面燃料孔数量使得中心回流区根部温度更低,有降低热力NOx的趋势;增加火焰筒直径,有助于中心回流区沿径向扩张,导致火焰更长、更细;将中心体端面改成椭圆,会缩短火焰轴向长度;改变中心体端面形状基本不影响火焰传递函数幅值和相位,但增加燃料孔数量明显改变火焰传递函数相位。

To analyse the dome structure of the lean premixed swirled combustor,the influences of lance tip shapes,inflow air flow rates,numbers and locations of fuel nozzles and head expansion ratios on the combustion flame,flow field and flame dynamic response were investigated by computational fluid dynamics.The results show that the flame shape remains unchanged when the air velocity increases to a certain value.Increasing the number of fuel holes on the pressure surface,the high heat release rate area is concentrated in the root of the central recirculation zone.While increasing the number of fuel injectors on the pressure side and suction side makes the flame root temperature of the central recirculation zone lower,indicating a tendency to reduce the thermal NOx.Increasing the flame tube diameter helps the central recirculation zone to expand radially,resulting in longer flame branches.The axial length of flame will be shortened by changing the centre-lance tip from flat to ellipse.The amplitude and phase of flame transfer function are not affected by changing the centre-lance tip face shape,but the phase of flame transfer function is obviously changed by increasing the number of fuel holes.