当量比对干式低排放燃烧室燃烧及NO_x生成影响的数值研究

Numerical simulation of influence of equivalence ratio on combustion and NO_x formation in a DLE combustor

采用数值模拟方法研究了干式低排放(DLE)燃烧室的流场结构及不同当量比对燃烧室内燃烧及污染物生成特性的影响。结果表明:中心回流区的高温回流燃气形成稳定的点火源,保证了燃料的着火和稳定燃烧;随着当量比的增大,燃烧室内流场变化较小,整体轴向速度略有增加,回流区范围基本不变;温度场变化较大,高温区明显扩大,整体温度上升,出口截面温度分布出现不对称的现象,下半侧高温区域面积略大于上半侧;出口NO_x排放摩尔分数明显上升,整体NO_x摩尔分数迅速上升,中心回流区附近增幅最为明显;旋流器的导向作用使燃烧室温度和热力型NO_x分布不均;降解当量比对控制DLE燃烧室NO_x排放有利。

The influence of flow field structure and equivalence ratio on combustion and pollutant emission characteristics of a dry low emission （DLE） gas turbine combustor is numerically studied. The results show that, the high temperature flow in the central recirculation establishes a firm aerodynamic base for flame stabilization. With an increase in the equivalence ratio, the flow field inside the combustor barely changes. The bulk radical velocity increases slightly, while the range of the recirculation areas barely changes. The temperature field changes greatly. The high temperature area expands significantly, and the bulk temperature rises clearly. The NOx formation rate and NOx concentration at the eombustor outlet both shows an obvious increase.