槽道纤维悬浮流稳定性的实验研究

Experimental Research on the Hydrodynamic Instability of Fiber Suspensions in Channel Flow

对槽道纤维悬浮流进行染色线流动显示和流场PIV实验测量,实验中选用的是直径为20μm、长径比为20～100的尼龙纤维。PIV2100处理器被用来加工处理采集的实验数据。槽道长度1.5m,横截面为矩形,尺寸为105×19mm。实验结果说明在Reynolds数相同的情况下,纤维悬浮流比对应的牛顿流更不容易失稳,悬浮流中的纤维起着抑制流场失稳的作用,而且随着纤维体积分数和长径比的增大,抑制失稳的程度也提高。扰动衰减率的最小值随纤维体积分数和长径比的增加而增大,这一效果在大Re数时更明显。

Dye emission techniques and PIV measurements were made to investigate the channel flows of fiber suspensions. In the experiments, the nylon fibers with 20μm long and 20~100 aspect ratio were used. PIV 2100 Processor was employed to treat the data recorded by instrument. The length of test section is 1.5m, the cross section is rectangular with a dimension of 105×19mm. The results show that the fiber suspension flow becomes unstable less easily than the Newtonian flow under the same Reynolds number. The fibers in the suspension play a role of suppressing the instability of the flow. The suppression effect of fibers on the instability becomes obvious with the increasing of the volume fraction and aspect ratio of fiber. The minimum of attenuation rate of disturbance rises with the increasing of volume fraction and the aspect ratio of fiber. This phenomenon is more evident at large Reynolds numbers.