The Characteristic of Flow Field and Emissions of a Concentric Staged Lean Direct Injection (LDI) Combustor

中心分级贫油直喷(LDI)燃烧室流动及污染排放特性研究

School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China

Received: 9 September 2017

Abstract

The characteristic of flow field and emissions was investigated by numerical simulation for a concentric staged lean direct injection combustor, the non-reaction and reaction flow fields were studied under idle and takeoff conditions, and the effect of combustion heat release on flow field was analyzed, then the influence of injection angle on emissions were obtained. The investigation results indicated that the steady central recirculation zone could be formed under non-reaction and reaction conditions by medium swirl strength which the swirl angle is 32°, however, the size and reverse mass flow at reaction conditions is significantly increased than non-reaction conditions; the combustion reaction zone moves toward the outlet as the decrease of fuel injection angle, which reduce the resistant time of hot gas in combustor, and then the production of nitrogen oxides would be decreased.

摘要

对中心分级贫油直喷燃烧室流动和污染排放特性进行了数值模拟研究，分别在慢车和起飞工况下研究了燃烧室冷态和热态的流动特性，分析了燃烧释热对流场形态的影响，得到了主油喷射角度对污染排放的影响规律。计算结果表明：副模采用旋流角为32°的中等强度旋流仍然能够在冷态和热态条件下形成稳定的中心回流区，但是热态下回流区尺寸和回流量较冷态显著增大；随着主油喷射角度的减小，燃烧反应区向下游方向移动，缩短了高温燃气在燃烧室内的停留时间，有利于降低燃烧室氮氧化物的生成量。