高分子减阻流场湍流结构实验研究

采用二维激光Ｄｏｐｐｌｅ测速仪，研究了聚丙烯酰胺（ＰＡＭ，平均相对分子质量５００万）稀溶液在方形管内减阻流场中脉动流速的时间相关系数变化规律。发现自相关系数随减阻率的增加而增大；在相同流量和聚合物质量分数下，管道横截面处脉动流速的自相关系数随管壁距离的变化而变化；在同一流量下，管中心处轴向和径向脉动流速－时间互相关系数随聚合物质量分数的增加而增大。

Study of correlation coefficients of fluctuating turbulent velocities under drag reducing conditions

The turbulent micro structure in pipe fluid flow and drag reducing conditions is studied with a two component coincident Laser Doppler Velocimeter(LDV). The correlation coefficients of the fluctuating turbulent velocities are calculated using high speed computing techniques. The results indicate that both the auto correlation coefficient and the time cross correlation coefficient of axial and radial fluctuating velocities under drag reducing condition are higher than in water. The concentration of PAM(average mol weight is 5 million g/mol) and the correlation coefficient are related to each other.