Morphology and displacement of dunes in a closed-conduit flow
Morphology and displacement of dunes in a closed-conduit flow
复制标题
闭管流中沙丘的形态和位移
DOI：
10.1016/j.powtec.2008.04.065
复制
发表时间：
2009
影响因子：
5.2
通讯作者：
F. Charru
中科院分区：
文献类型：
--
作者：
E. Franklin;F. Charru
在工业应用中经常发现封闭管道流体流动所携带的固体颗粒的输送。例如，在石油、食品和制药工业中可以找到它。关于固体颗粒的大小，可能存在几个数量级：从几十微米到几十毫米。因此，更好地了解这种输送及其相关的压降对改进与颗粒有关的工业过程具有重要意义。然而，到目前为止，它在理论上还没有得到很好的理解。当流体在颗粒床上施加的剪切应力能够移动它们中的一些，但与颗粒的表观重量相比相对较小时，就会发生称为床载的可移动颗粒层，其中颗粒与固定床保持接触。这个可移动层的厚度是几个粒子直径。床荷载的存在取决于两种力的平衡：a)流体动力性质的夹带力，与τd2成正比，其中τ为床层剪切应力，d为平均颗粒直径；B)与粒子表观重量相关的阻力，与（ρs−ρ） gd3成正比，其中ρ为流体密度，ρ为粒子密度，g为重力加速度。
The transport of solid particles entrained by a closed-conduit fluid flow is frequently found in industrial applications. It is found, for example, in the petroleum, food and pharmaceutical industries. Concerning the size of the solid particles, several orders of magnitude may be present: from some tens of microns to some tens of millimeters. A better knowledge of this kind of transport and of its associated pressure drop is then of great importance to improve particle related industrial processes. Nevertheless, up to now, it has not been theoretically well understood. When shear stresses exerted by the fluid flow on the bed of particles are able to move some of them, but are relatively small compared to particles apparent weight, a mobile layer of particles known as bed-load takes place in which the particles stay in contact with the fixed bed. The thickness of this mobile layer is a few particle diameters. Bed-load existence depends on the balance of two forces: a) an entraining force of hydrodynamic nature, proportional to τd2, where τ is the bed shear stress and d is the mean particle diameter; b) a resisting force related to particles apparent weight, proportional to (ρs− ρ) gd3, where ρ is the fluid density, ρs is the particles density and g is the gravitational acceleration.