运用粒子成像测速仪（PIV）对壁面雷诺数为Re_τ=430、质量载荷为0.25×10（-3）～5×10（-3）的110μm聚乙烯颗粒加入前后的水平槽道湍流变动进行了研究。实验结果表明低载荷下气相湍流变动源于颗粒对湍流拟序结构的作用。颗粒的存在抑制了湍流拟序结构的发展,使得湍流准流向结构长度减小、猝发频率降低、猝发强度减弱;另外,颗粒尾涡脱落还导致了壁面附近的气相剪切雷诺应力增强。
Turbulent modulations are experimentally investigated using particle image velocimetry （PIV）in the lower boundary layer of a fully developed horizontal channel flow.Polythene beads with diameter of 110μm are used as dispersed phases.Measurements are performed at three mass loadings varying from 2.5×10~（-4）to 5×10~（-3）.The experimental results show that the effect of particles on the near-wall quasistreamwise vortices is the key mechanism for the gas phase turbulence modulation at low mass loading.The presence of the particles degrades the coherent structures, with shorter streamwise extent,lower burst frequency and weaker burst strength.In addition,as a result of the particle wake,the shear Reynolds stress of gas phase increases in the vicinity of the wall.
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