一级旋流入射半径对小尺寸旋流杯下游流动特征的影响

Effects of primary swirl flow incident radius on flow characteristics downstream of small size swirl cups

为探索一级旋流入射半径对小尺寸旋流杯下游流动特性的影响,采用PIV测速技术对小尺寸旋流杯下游速度分布特征进行了试验测量。结果表明:不同入射半径的一级旋流会形成扩张流场或扩张-收缩-扩张流场;入射半径方向相反、数值不同将对旋流杯下游流动产生不同影响;旋流杯下游流场涡量分布与同一方案的速度分布相似,旋流杯出口平均涡量较强的旋流沿流向涡量逐渐衰减,且速率变缓;不同一级旋流入射半径的旋流杯方案的平均涡量变化趋势基本一致。在所研究的试验状态下,一级旋流入射半径对小尺寸旋流杯下游速度和涡量分布特征产生了较大的影响。

In order to explore the impacts of primary swirl flow incident radius on flow characteristics down stream of small size swirl cups,experiments have been carried out to measure velocity distribution of differ ent swirl cups.The study of flow field was focused on the variations of primary swirl flow incident radius.It is found that two different flow patterns are formed due to the primary swirl flows with different incident ra dii: the expanding flow pattern and the expanding-contracting-expanding pattern.The difference among the downstream swirl flows are caused by different directions of flow incidence and different incident radius values.The distributions of velocities and vorticity with the same swirl cup are similar.The vorticity of the swirl flow decreases with the longitudinal distance increasing,and the decreasing rate gradually slows down.The variation tendencies of average vorticities are basically the same with all the swirl cups.Under the test condition of this study,incident radius of primary swirl flow could have large impact on the distribu tions of velocities and vorticity downstream of small size swirl cup.