论文标题
静电电荷对含量颗粒管流的影响
The effect of electrostatic charges on particle-laden duct flows
论文作者
论文摘要
我们报告了直接的数值模拟静电电荷对颗粒导管流的影响。已知相应的静电力会在小尺度和相关的涡轮流漂移下影响颗粒动力学。但是，我们的模拟预测，静电力也主导着颗粒的涡旋运动，这是由Prandtl第二种载体流体的次级流动引起的。在此，我们以两个摩擦雷诺的数量（$ re_ \mathrmτ= $ 300和〜600），两个粒子与气体密度比（$ρ_\ mathrm {p}/ρ= $ 1000和7500）和三个coulombicto to-gravitational form（$ f _ $ f _ $ nmerm} 0、0.004和0.026）。在$ re_ \mathrmτ= $ 600和$ f_ \ mathrm {el}/f_ \ mathrm {g} = $ 0.004时，高密度比的流量为$ re_ \mathrmτ= $ 600，粒子往往会在墙壁上积累。另一方面，以较低的密度比分别以0.026的较高$ f_ \ mathrm {el}/f_ \ mathrm {g} $为0.026，带电粒子仍然遵循管道中开发的二级流结构。然而，即使在这种情况下，静电力也抵消了壁上的颗粒向内通量，结果，它们在这些二次结构中的涡旋运动也会显着减弱。与带有未充电颗粒的相应流相比，流动模式的这种变化导致壁上的颗粒数密度增加了5倍。 Finally, at $Re_\mathrmτ=$ 300, $ρ_\mathrm{p}/ρ=$ 1000, and $F_\mathrm{el}/F_\mathrm{g}=$ 0.026 the electrostatic forces dominate over the aerodynamic forces and gravity and, consequently the particles no longer follow the streamlines of the carrier gas.
We report on direct numerical simulations of the effect of electrostatic charges on particle-laden duct flows. The corresponding electrostatic forces are known to affect particle dynamics at small scales and the associated turbophoretic drift. Our simulations, however, predicted that electrostatic forces also dominate the vortical motion of the particles, induced by the secondary flows of Prandtl's second kind of the carrier fluid. Herein we treated flows at two frictional Reynolds numbers ($Re_\mathrmτ=$ 300 and~600), two particle-to-gas density ratios ($ρ_\mathrm{p}/ρ=$ 1000 and 7500), and three Coulombic-to-gravitational force ratios ($F_\mathrm{el}/F_\mathrm{g}=$ 0, 0.004, and 0.026). In flows with a high density ratio at $Re_\mathrmτ=$ 600 and $F_\mathrm{el}/F_\mathrm{g}=$ 0.004, the particles tend to accumulate at the walls. On the other hand, at a lower density ratio, respectively a higher $F_\mathrm{el}/F_\mathrm{g}$ of 0.026, the charged particles still follow the secondary flow structures that are developed in the duct. However, even in this case, the electrostatic forces counteract the particles' inward flux from the wall and, as a result, their vortical motion in these secondary structures is significantly attenuated. This change in the flow pattern results in an increase of the particle number density at the bisectors of the walls by a factor of five compared to the corresponding flow with uncharged particles. Finally, at $Re_\mathrmτ=$ 300, $ρ_\mathrm{p}/ρ=$ 1000, and $F_\mathrm{el}/F_\mathrm{g}=$ 0.026 the electrostatic forces dominate over the aerodynamic forces and gravity and, consequently the particles no longer follow the streamlines of the carrier gas.
