Abstract Resistance reduction has always been a concerning problem in pipeline transportation projects. Moreover, adding fine particles has shown resistance reduction. Therefore, we studied the effect of adding finer particles on the transport characteristics of coarse-particle slurries in pipelines. The flow conditions and slurry characteristics, such as the flow velocity and particle volume concentration, and the addition of finer particles can reduce the resistance of coarse-particle slurries under certain working conditions. In this study, the changes in the transport characteristics of slurries with 0.44 mm diameter glass balls after adding an equal volume of 0.125 mm diameter glass balls under different flow velocities and volume concentrations were analysed. The effects of adding fine particles on the transport characteristics of coarse particles under different flow conditions were determined, including the distributions of the particle volume concentration, velocity, particle pressure, and wall shear stress. We observed that adding fine particles could change the flow regime of coarse particles near the critical flow velocity (from sliding bed to heterogeneous flow), thereby considerably reducing the pipeline resistance (by approximately 20%). At a high flow velocity (heterogeneous or homogeneous flow), the addition of fine particles will increase the resistance. The study results explain the mechanism and characteristics of resistance reduction on adding fine particles from the perspective of changing the flow regime. These findings can serve as a reference for further studying the resistance reduction mechanism on adding fine particles and for finding the optimal particle size distribution for slurry transport in pipelines.

中文翻译：

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添加细颗粒对粗颗粒泥浆在管道中输送特性的影响

摘要 降阻一直是管道运输工程中关注的问题。此外，添加细颗粒显示电阻降低。因此，我们研究了添加细颗粒对管道中粗颗粒浆料输送特性的影响。流动条件和浆料特性，如流速和颗粒体积浓度，以及加入更细的颗粒可以降低粗颗粒浆料在某些工况下的阻力。本研究分析了在不同流速和体积浓度下加入等体积 0.125 mm 直径玻璃球后含 0.44 mm 直径玻璃球的浆料输运特性的变化。确定了在不同流动条件下添加细颗粒对粗颗粒输运特性的影响，包括颗粒体积浓度、速度、颗粒压力和壁面剪切应力的分布。我们观察到添加细颗粒可以改变临界流速附近粗颗粒的流动状态（从滑动床到异质流），从而大大降低管道阻力（约 20%）。在高流速下（非均质或均质流），加入细颗粒会增加阻力。研究结果从改变流态的角度解释了加入细颗粒时阻力降低的机理和特点。