一级旋流强度对双旋流杯下游油气分布的影响

Effects of Primary Swirl Intensity on Flow and Fuel Distribution Downstream a Dual-Swirl Cup

关键词:  航空发动机  燃烧室  旋流杯  旋流数  切向动量矩

Key words:  Aero-engine  Combustor  Swirl cup  Swirl number  Tangential momentum moment

摘要:

为了改善双旋流杯点火性能，需要优化其下游的流场和油雾场。利用激光粒子动态分析技术(PDA)测量基准双旋流杯下游的流场和油雾场，据此提出一级旋流器旋流数仅增大6.7%，但切向动量矩减小44%的改进方案，并进行了流场和油雾场对比试验。试验结果表明:减小双旋流杯一级旋流切向动量矩会使旋流杯下游流场结构发生较大变化，使其从收扩型转变为扩张型，同时减小油雾的索太尔平均直径(SMD)；当与旋流杯出口距离超过2.5倍文氏管喉道直径时，流场输运和油滴蒸发作用增强，使得油雾分布更加均匀，燃油SMD更小。在航空发动机燃烧室双旋流杯设计中，不仅要考虑传统的旋流数概念，还应考虑各级切向动量矩的综合影响作用。

Abstract:

In order to improve the ignition performance of dual-swirl cup，the downstream flowfield and fuel distribution should be optimized. The flowfield and fuel distribution downstream a baseline dual-swirl cup were measured by Particle Dynamics Analyzer (PDA). Based on the results，an improved dual-swirl cup scheme was proposed with only 6.7% increase of swirl number and 44% decrease of tangential momentum moment for the primary swirl，and the flowfield and fuel distribution were measured and compared with the baseline one. The experimental results indicate that the reduced tangential momentum moment of the primary swirl will affect the flowfield downstream the dual-swirl cup，and then change the flowfield structure from converge-diverge type to diverge one and decrease the Sauter Mean Diameter (SMD) of the fuel spray. When the distance downstream the swirl cup reaches 2.5 times the venturi throat diameter，the effect of flowfield transportation and droplet evaporation could be enhanced to make fuel distribution more uniform and SMD smaller. Both the swirl number and tangential momentum moment of swirlers should be considered in dual-swirl cup design for aeroengine combustor.