中心分级燃烧室预燃级的喷雾特性研究

Experimental Investigation on Pilot Spray Characteristic of Internally-Staged Combustor

关键词:  航空发动机  燃烧室  预燃级  流场  回流区  雾化

Key words:  Aero-engine  Combustor  Pilot stage  Flow field  Recirculation zone  Atomization

摘要:

为研究典型中心分级燃烧室预燃级的冷态喷雾特性，进行了实验研究。应用相位多普勒粒子分析仪（PDA）测量液滴的直径和速度，应用片光照相得到喷雾照片。实验结果表明：由于受到套筒结构的限制，预燃级喷雾锥角较小，一般在50°～70°，随着燃油流量和空气压降的增加，喷雾锥角增大，燃油分布范围更广，液滴数量增加，直径随之变小。预燃级的中心回流区宽度仅为20mm左右，一直延伸进套筒内，最大回流速度约为10m/s。燃油流量的改变对流场的影响十分微弱，而空气压降的增加能够明显增加流场速度和回流强度，但是工况参数的改变并不会改变回流区位置和流场结构。燃油流量的减小和空气压降的增加都会使雾化索太尔平均直径（SMD）减小，但相比之下，空气压降对雾化水平的影响更大。在各头部空气压降下，雾化SMD随着气液比（ALR）的增加而减小，但随着ALR的继续增加，平均SMD变化曲线变平缓。

Abstract:

In order to investigate the pilot spray characteristic, a series of experiment was taken. Phase doppler particle analyzer (PDA) was used to measure size and velocity of droplets. The photos of spray were captured with a light sheet. The results are asconclusion spray corn angle ranged from 50° to 70°, it seemed quite small due to the restriction of sleeve. With increasing fuel mass flow rate or air pressure drop, spray corn angle became larger, and the spray ranged broader. The quantity of droplet increased and drop diameter decreased. The width of the center recirculation zone was merely 20mm, and the maximal recirculate velocity was about 10m/s. Changes of fuel mass flow rate hardly influenced the air flow field while increasing air pressure drop lead to obvious enhance of flow velocity and circulation. However, the position of circulation zone and the structure of flow field did not charge with the variation of the operating conditions. The increase of air pressure drop as well as the decrease of fuel mass flow contributed to the decrease of Sauter mean diameter (SMD), but the changes of air pressure drop mattered more. At a certain air pressure drop, the average SMD decreased with the rising of air-liquid ratio (ALR), however the curve flattened out as the increase of ALR.