论文标题
弱静电电荷和次要流对气粉传输的影响
Influence of weak electrostatic charges and secondary flows on pneumatic powder transport
论文作者
论文摘要
运输粉末的动力学决定了气动输送系统的功能和安全性。对于静电电荷的颗粒而言，载气流量和粉末流量模式诱导的载气流量和粉末流动模式之间的关系尚不清楚。本文强调了相对较小的横截面次要流和静电力对颗粒浓度和动力学的影响。为此，直接数值模拟（DNS）通过四向耦合的欧拉 - 拉格朗日策略捕获了连续和分散阶段的相互作用。将弱带电颗粒在通道流中的转运，其中涡轮变形定义了颗粒浓度，与导管流进行了比较，在其中形成了其他横截面涡旋。对于两种几何，Stokes编号（$ S \！t = 8，32 $）和电气stokes编号（$ s \！t_ \ mathrm {el} = [0，1，2，4] \ times 10^{ - 3} $）是多种多样的，湍流的载体流量固定为$ re_ re_ re_ re_ pre_fe_τ= 360 $。提出的模拟表明，对于相同的$re_τ$，$ s \！t $和$ s \！t_ \ mathrm {el} $，辅助流量降低了粒子电荷的效果。在管道流中，涡流次级流动增强了针对静电力方向的横截面粒子迁移率。与管道流相比，在通道中，壁正常空气动力较弱。因此，电力主导其运输；壁上的局部颗粒浓度增加。此外，静电电荷在气体和颗粒速度之间导致更强的相关性。总之，尽管与原发性流动力相比，次级流量和静电力在气动转运过程中驱动颗粒动力学。
The dynamics of the transported powder determines the functionality and safety of pneumatic conveying systems. The relation between the carrier gas flow, induced by the flown-through geometry, and the powder flow pattern is not clear yet for electrostatically charged particles. This paper highlights the influence of relatively minor cross-sectional secondary flows and electrostatic forces on the concentration and dynamics of the particles. To this end, direct numerical simulations (DNS) capture the interaction of the continuous and dispersed phases by a four-way coupled Eulerian-Lagrangian strategy. The transport of weakly charged particles in channel flows, where turbopheresis defines the particle concentration, is compared to duct flows, where additional cross-sectional vortices form. For both geometries the Stokes number ($S\!t=8, 32$) and the electrical Stokes number ($S\!t_\mathrm{el}=[0, 1, 2, 4]\times 10^{-3}$) are varied, the turbulent carrier flow was fixed to $Re_τ=360$. The presented simulations demonstrate that secondary flows, for the same $Re_τ$, $S\!t$, and $S\!t_\mathrm{el}$, dampen the effect of particle charge. In a duct flow, vortical secondary flows enhance the cross-sectional particle mobility against the direction of electrostatic forces. Compared to a duct flow, in a channel the wall-normal aerodynamic forces are weaker. Thus, electrical forces dominate their transport; the local particle concentration at the walls increases. Further, electrostatic charges cause a stronger correlation between the gas and particle velocities. In conclusion, despite being weak compared to the primary flow forces, secondary flow and electrostatic forces drive particle dynamics during pneumatic transport.
