双球颗粒对平板边界层流场结构的影响

Effect of two-sphere particles on flow field structure of flat plate boundary layer

为掌握边界层粒子周围的流动结构,利用粒子图层测速(PIV)技术在雷诺数为500~2000范围内,对3种不同直径、6种不同间距下的粒子周围的流场特性进行了测量.对流场特性分析的结果表明,随着流体速度和粒子直径的增加,粒子后端的漩涡区域逐渐被增强,会形成单个漩涡、镜像对称漩涡、一大一小旋向相反漩涡3种模式.在观测的试验粒子中,10 mm粒子后端的漩涡区域最为显著;当粒子间距增大到一定阈值后,粒子后端的漩涡区域便不再随着间距的增大而被增强.研究结果为进一步揭开边界层粒子周围的流动结构提供了试验依据.

To comprehend the flow structures surrounding particles within the boundary layer,particle image velocimetry(PIV)technique was employed to measure the flow field characteristics around particles of three distinct diameters and six different spacings within the Reynolds number range of 500 to 2000.The analysis results of the flow field characteristics reveal that with escalating fluid velocity and particle diameter,the vortex region behind the particles progressively intensified,exhibiting three distinctive modes:a singular vortex,mirror-symmetric vortices,and large-small oppositely rotating vortices.Among the observed experimental particles,the vortex region behind 10 mm particles displayed the most pronounced characteristics.However,upon reaching a certain threshold of particle spacing,the enhancement of the vortex region behind the particles ceased with further increases in spacing.These research findings serve as experimental evidence toward further elucidating the flow structures around particles within the boundary layer.