旋流强度对F级燃气轮机燃烧稳定性影响分析

Influence of Swirl Strength on the Combustion Stability in F-Class Gas Turbine

旋流器是目前燃烧室中常用的稳定火焰的结构,主要通过气体经过旋流器后在下游形成的回流区来稳定火焰。一般采用旋流数表征旋流器的旋流强度。旋流数一方面会影响空气和燃料的掺混,另一方面会影响回流区的尺寸,从而对火焰的长度和稳定性产生影响。针对某重型燃气轮机的燃烧器,采用数值模拟的方法分析了旋流数变化对热态温度场的影响,同时采用三维有限元方法分析了旋流数对燃烧稳定性的影响。结果表明:旋流数增加,会使得火焰更加紧凑,长度缩短,同时使得燃烧室二阶周向模态稳定性恶化,不稳定的风险增加;降低旋流数会使得火焰长度增加,轴向模态稳定性恶化。该研究结果可为类似机组的相关设计研究提供参考和借鉴。

Swirler is commonly used to stabilize the flame in the combustion chamber.After the air passes through the swirler,a recirculation zone is formed to stabilize the flame.The swirl strength is characterized by swirl number.Swirl number not only affects the mixing of air and fuel,but also has influence on the dimension of the recirculation zone,thus affects the length and stability of the flame.Aimed at the combustor in a certain type of heavy duty gas turbine,numerical simulation method is applied to analyze the influence of swirl number on the temperature field,and 3D FEM is used to analyze its influence on the combustion stability.The results are showed as follows:with the increase of the swirl number,the flame becomes shorter,the stability of second circumferential mode in the chamber begins to deteriorate,and the risk of the instability increases;with the decrease of the swirl number,the flame becomes longer,and the stability of axial mode in the chamber begins to deteriorate.The research result can provide reference for the relevant design and research of similar units.