低压模化对燃气轮机燃烧室工作特性影响的数值分析

为研究低压模化对于燃气轮机燃烧室工作特性的影响,采用ANSYS软件的FLUENT模块,对燃烧室在低压模化以及低压1/3尺寸模化条件下的燃气轮机燃烧室分别进行数值模拟研究,并与在全压条件下的燃烧室计算结果进行对比分析。计算结果表明:在低压模化条件下,燃烧室的流线形态与全压下基本相同;由于压力对于化学反应平衡的影响,在低压条件下燃烧室的壁温相比在全压下的平均降低70~100 K,其出口温度场指标比在全压下的更好;由于受燃烧室入口空气压力的影响,在低压条件下燃烧室的燃烧效率和流阻损失均比在全压下的低;另外,由燃烧室压力和尺寸的变化引起的燃烧室内温度分布变化,造成NO源分布的不同及燃烧室内NO的生成速率发生巨大变化,导致燃烧室NOx的排放水平不同,并验证了压力指数。其计算结果可为燃气轮机燃烧室的低压和常压模化试验提供参考。

Numerical Analysis on Influence of Low Pressure Modeling on Operation Characteristics of Gas Turbine Combustor

In order to study the influence of low pressure modeling on operation characteristics of gas turbine combustor, the full-size gas turbine combustor and its 1/3 size model combustor at low pressure condition were simulated by using FLUENT model of ANSYS software, and the calculation results were compared with full-size combustor in full pressure condition. The simulation results show that in low pressure condition, streamline distribution in the combustor are substantially the same as that in full pressure condition. Due to affect of on the pressure chemical reaction equilibrium, the liner wall temperature in low pressure condition is averagely 70 K to100 K lower than that in full pressure condition, and the outlet temperature pattern factor in low pressure conditions is better. Because of the impact of inlet pressure, combustion efficiency and total pressure loss in low pressure condition are lower than in full pressure condition. In addition, because of the temperature distribution change in the combustor caused by the change of combustor pressure and size, the distribution of NO sources and the growth rate of NO change a lot, so NOx emissions in three different conditions are much different. Furthermore, the pressure impact index is verified. The results can provide references for gas turbine combustor low-pressure and atmospheric pressure test.