中文摘要：

发展低NOx燃烧技术，一个主要方法是通过分级燃烧组合燃烧过程来满足工况下的低污染排放要求。实现该技术的一个关键技术是如何在运行中避免或控制非稳定振荡燃烧。通过对分级燃烧系统的非稳态数值模拟，可以看到燃烧系统动态特性不仅与每个进口的安排有关，也和频率密切相关。通过构建火焰传递函数，可以定量分析火焰动态变化的大小和它们之间的相位关系。这些结果可以帮助我们在设计和运行分级燃烧系统时，防止可能出现的振荡燃烧，实现燃烧系统在全工况下安全、高效运行。

英文摘要：

One of the methods reducing NOx emission in gas turbine combustion is the dry low emission （DLE） with staged combustion technique. With this technique, the number of burners and their modes are manipulated according to the requirement of loading, so that the low emission can be obtained in the whole power range of operation. To achieve this objective, the major technical challenge is to develop the method to avoid or control the unsteady combustion oscillations. In this paper, we investigate the staged combustion oscillations mechanisms with numerical simulation. At the beginning, the unsteady combustion processes within the staged combustor were calculated with the computational fluid dynamics （CFD） method. It is shown that the flame dynamics are greatly depend on the both inlet positions and forcing frequencies. The results show that the operating conditions have significant effects on combustion stabilities. The work can help to control staged combustion operating in the range of stable conditions, and to avoid the combustion oscillation. This will make combustion system operating safe, efficient and clean.