含聚丙烯酰胺的管道螺旋流壁面切应力试验

Experiments on the wall shear stress of the pipeline spiral flow containing polyacrylamide

为了了解聚丙烯酰胺对管道螺旋流输固能力的影响,搭建了管道试验系统。采用直球头5孔测针和1套水压力测压系统,测量5孔测针测孔内动水压强,计算壁面切应力并构造有效起旋距离参数,评价加入聚丙烯酰胺对管道螺旋流输固能力的影响。试验结果表明:5孔直球头测针实测壁面切应力要比Preston法率定值偏大3%～5%,5孔直球头测针可以测量一维清水管道直流壁面切应力。壁面切应力(周向分量)随着流量的增加而增加,随着流向距离的增加而递减并在某一位置开始线性衰减。加入聚丙烯酰胺(100mg/L)之后,其有效起旋距离(力学指标)提升效果为100%～150%,提升效果随着流量的增加而减小,表明加入少量聚丙烯酰胺能够提升管道螺旋流的输固能力。

For understanding the effect of polyacrylamide on the transport capacity of pipeline spiral flow, an experimental facility of pipeline system is built. 5 holes stylus and one pressure measuring system are used to measure the dynamic water pressure of 5 holes stylus. Thus, the wall shear stress is calculated to construct parameters of effec rive staring distance for evaluating the effect on the transport capacity of pipeline spiral flow after adding polyacrylamide. The results show that the measured wall shear stress is 3%-5% larger than Preston＇s law rate,then the 5 hole stylus can be used to measure the wall shear stress of 1 D flow. The wall shear stress （circumferential component） in creases with the increase of the flow rate, decreases with the increase of the flow direc tion distance and decreases linearly at a certain position. The effective starting distance （mechanical parameter） increases with the increase of flow rate, and the promoting effect which decreases with the flow rate is 100%-150% after the addition a amount of poly acrylamide. The transport capacity of pipeline spiral flow is improved after adding a small amount of polyacrylamide.