燃气轮机双燃料燃烧室流场对比数值研究

针对燃气轮机环管型双燃料燃烧室分别燃用庚烷和裂解气燃料的情况,采用CFD(computa-tional fluid dynamics)技术对其燃烧流场进行对比研究.数值模拟采用了RNGk-ε湍流模型、化学平衡条件下的快速化学反应系统和简单概率密度函数(PDF)燃烧模型、液体燃料的喷雾模型以及SIMPLE算法.模拟对比分析了两种燃料燃烧下的温度分布、燃烧效率、流量分配、壁面冷却效果、空气过量系数等参数,以及它们随工况变化的趋势.所得结论如下:①不同燃料燃烧时,流场内的流量分配基本保持一致;②裂解气燃料燃烧时,其燃烧效率高出燃油状态约1%,但出口温度均匀性较差;③在加入相同化学焓值的燃料进入燃烧室时,裂解气燃料的头部空气过量系数α较大,所得到的出口平均温度低于燃油状态约20～40 K. 

Comparative numerical simulation of combustion flows in a dual-fuel-combustor

Combustion flows with different fuels as heptane and pyrolysis gas in a dual-fuel-combustor of gas turbine were simulated by a CFD(computational fluid dynamics) method.The RNG(renormalization group) k-ε turbulence model,single chemistry reaction system,infinite-rate reaction velocity,discrete phase modeling for liquid fuel,upwind discretization scheme and the SIMPLE algorithm were applied.Some performances of combustor such as: combustion efficiency,temperature uniformity at outlet,temperature distribution of walls,distribution of air mass flow and the first air excess coefficient,were also analyzed.Some results show that: 1) the distribution of mass flow rate is consistent with different fuels,2) there is a 1% higher combustion efficiency and lower temperature uniformity at outlet with pyrolysis gas than that of oil fuel,3) the average temperature at outlet with pyrolysis gas is 20～40K lower than that of oil fuel with the same chemical enthalpy injected in the combustor,and 4) the first air excess coefficient α of pyrolysis gas is higher than that of oil fuel.