Abstract: A single annular lean-burn internally-staged combustor consists of pilot stage and main stage.The pilot stage is located in the center-line of the combustion chamber while the main stage surrounds coaxially the pilot stage. There exists a physical isolation called step height between the two stages. The emission tests using a single module rectangular combustor were operated under the idle condition to study the effects of step height on NO_x. The commercial software Fluent was used to simulate the cold flow field and combustion performance. The results indicate that step height has a great influence on the emission of NO_x. When the step height increases by 38%，the surface and volume of primary center recirculation zone will increase by 6.7% and 16.4%. However，the axial length has a decrease of the small amount and the emission of [EINO_x]will increase by 35.1%.

Key words: Aero-engine；Internally-staged combustor；Step height；Numerical simulation

摘要： 一种单环腔中心分级低污染燃烧室，由中心的预燃级和外围的主燃级构成，在主预燃级之间存在一定的物理隔离(台阶高度)，为了研究主预燃级之间不同台阶高度对氮氧化物(NO_x)排放的影响，在慢车工况参数下，采用单头部矩形试验件进行了污染排放测试试验，并利用Fluent商用软件进行了冷态流场和热态燃烧性能的数值模拟分析。结果表明:台阶高度对NO_x排放有很大影响，当台阶高度增大38%，中心回流区表面积增大6.7%，体积增大16.4%，轴向长度有所减小，NO_x排放指数升高35.1%。

关键词: 航空发动机；中心分级燃烧室；台阶高度；数值分析