覆盖多孔介质的圆柱尾迹实验研究  

Experimental study on the wake of a circular cylinder with porous layer coating

作　　者：魏峥[1,2] 夏超[1,2] 袁海东[1,2] 李启良[1,2] 杨志刚[1,2] 

机构地区：[1]上海市地面交通工具空气动力与热环境模拟重点实验室,上海201804 [2]同济大学上海地面交通工具风洞中心,上海201804

出　　处：《空气动力学学报》2017年第2期265-270,289,共7页Acta Aerodynamica Sinica

基　　金：国家重点研发计划课题(2016YFB1200503-04)

摘　　要：利用风洞试验研究了多孔介质对圆柱绕流的影响,通过热线、烟线和粒子图像测速对有/无覆盖多孔介质柱体尾迹的频率特征、平均流场和瞬时流场进行了测量和分析,进而探究多孔介质与流场之间的作用机理。结果表明:引入多孔介质后,尾迹的大尺度涡脱落结构得到有效抑制,圆柱涡脱落频率降低;多孔介质减弱了近尾迹场的速度功率谱密度峰值,增大了远场的速度功率谱密度峰值,涡脱落位置延后;多孔介质减小了尾迹区的速度,拓宽了尾迹的宽度,使得两侧剪切层变得细长,削弱了它们之间的相互作用,减缓了两侧涡相互作用的速率;同时,多孔介质减小了尾迹区的速度脉动以及雷诺应力,雷诺应力和平均涡量的峰值更加远离圆柱,减弱了剪切层的不稳定性,增大了涡形成长度。The effects of porous media on the flow around a circular cylinder were investigated experimentally using the synchronous measurement of hot-wire anemometry, smoke-wire visualization and particle image velocimetry （PIV）. The frequency characteristics, time-average and instantaneous flow field of the wake were measured and analyzed for improving understanding on the mechanism of flow modification caused by porous layer coating. The results show that the large-scale vortex shedding structure is effectively inhibited with porous layer coating and the Strouhal number of vortex shedding is 0. 162 for the porous one which is smaller than 0. 182 for the bare one. Additionally, the peak power spectral density of velocity is decreased in the near wake （x/D≤1. 5）, while increased in the far wake（x/D〉1. 5） and the position of obvious vortex shedding shifts downstream. Porous media attenuate the velocity of the wake region and widen the wake, leading to the weaker interaction between the two slenderer shear layers and slower rate of vortex interaction. Meanwhile, the porous media significantly eliminate the velocity fluctuations in the streamwise and spanwise, especially in the centerline as well as the Reynolds stress in the wake. The positions of peak value of Reynolds stress and time-averaged vorticity are more far away from the cylinder, so that the porous media weaken the instability of the shear layer and increase the vortex formation length.

关 键 词：圆柱 多孔介质 尾迹 粒子图像测速 

分 类 号：V211.7[航空宇航科学与技术—航空宇航推进理论与工程]