物料管道输送的减阻问题

为了提高输送效率和节约能源，使用振动减阻的方法来实现物料的输送减阻，尾砂试验表明，振动减阻是切实可行的，而浆体的浓度和输送速度是两个关键性因素，通过应力液的反射与透射分析，认为应力波在管道垂直方向上传播时逐渐衰减，迫使下层颗粒向上作微波移动，降低了浆体的粘性阻力损失，管道振动对层流附面层有较大影响，使边壁浆体的速度梯度减小，并导致边壁剪切应的降低。同时，使附面层的厚度加大，中性稳定雷诺数增加，阻止流态的转捩。应力波的作用以及附面层的改变，最终导致输送阻力的降低。

Study on Drag Reduction of Materials Transported by Pipeline

In order to improve the efficiency and save the energy,many kinds of methods are used to reduce the drag of materials transported by pipeline.Firstly,some kinds of the methods are overviewed,then a new method,the vibration drag reduction,is elaborated.The experimental result of tailings shows that the new method is practical,and the slurry concentration and the transportation speed are two key factors.By the analysis of the reflection and transmission of the stress wave in the slurry,it is considered that when the wave is travelling through the slurry in a direction perpendicular to the axis of the pipeline,its amplitude decays gradually with travelled distance,which forces the granules in the lower layer a small upward movement,thereby resulting in the reduction of the damping of the slurry.The vibration of the pipeline has great influence on the boundary layer of a laminar flow,which leads to the decrease in the speed gradient and the shear stress of the slurry near the edge.As a result,the action of stress wave and the change of boundary layer make the drag of transportation decrease.