偏转角影响磁纤维捕集Fe基细颗粒的数值模拟

为了研究磁性纤维对钢铁行业细颗粒物的控制效果，基于计算流体力学-离散相模型（CFD-DPM）对高梯度磁场中含尘气流方向与背景磁场方向夹角（偏转角）分别为0°、15°、30°、45°、60°、75°、90°时磁性单纤维捕集Fe基细颗粒进行数值模拟.分别研究高梯度磁场作用下颗粒粒径、入口风速、磁场强度对颗粒运动轨迹和捕集效率的影响.结果表明：高梯度磁场中偏转角影响磁性纤维捕集区域的位置，当角度为0°时，在纤维正对含尘气流方向区域形成颗粒捕集区，背风侧形成较大空腔；当角度为90°时，在沿气流方向纤维两侧形成面积相等的捕集区域.偏转角对小颗粒捕集效率的影响较小，当角度为0°时，对于0.5μm的颗粒捕集效率为4.1%，当角度为90°时捕集效率为3.9%.随着粒径的增大，捕集效率的增长速率先减小后增大，对于不同粒径的颗粒，当角度为0°时捕集效率最高.当风速在0.02~0.04m/s范围时，随着角度从0°增加到90°，捕集效率先降低，在45°附近达到最小值，然后升高.磁场强度的增加有利于提高捕集效率，但不同角度时的增长速率有所不同.当偏转角为0°和60°时，背景磁场强度为0.1~0.3T范围时增长速率明显大于0.3~0.9T范围内，而当偏转角为30°和90°时，背景磁场强度为0.1~0.5T范围时增长速率高于0.5~0.9T时的增长速率.

Numerical simulation of the entrapment of Fe-based fine particles by magnetic fibers with different deflection angles

To reveal the mechanism of the entrapment of fine particles generated from the iron and steel industry by magnetic fibers, numerical simulation based on the Computational Fluid Dynamics-Discrete Phase Model (CFD-DPM) was used to simulate the capture of Fe-based magnetic fine particles by magnetic single fibers in high gradient magnetic fields when the deflection angles between the dust flow direction and the background magnetic field direction was set at 0°, 15°, 30°, 45°, 60°, 75° and 90°. The effects of particle size, inlet wind speed and magnetic field intensity on the particle trajectory and the trapping efficiency were studied in high gradient magnetic field. The results proved that the deflection angle controlled the region of the fine particle entrapment by magnetic fibers. When the deflection angle was set at 0°, a particle trapping region was formed in front of the fibers facing the wind incoming direction, and a large cavity was generated on the leeward side. As the deflection angle was shifted to 90°, the particle trapping regions were formed on both sides of fibers along the dust flow direction. The deflection angle exerted less effects on the entrapment of smaller particles. The capture efficiency of particles around 0.5μm was 4.1% at a deflection angle of 0°, while the efficiency only shifted to 3.9% when the deflection angle was changed to 90°. With the increase of the particle size, the entrapment efficiency decreased first and then raised. For all the particles with different sizes, the trapping efficiency was the highest when the deflection angle was at 0°. Along with the rise of the deflection angle from 0° to 90°, in the wind speed range from 0.02 to 0.04m/s, the trapping efficiency reduced first to achieve a minimum value at around 45° and then increased. The enhancement in magnetic field intensity could promote the trapping efficiency, but the elevation rate varied at different deflection angles. When the deflection angle was set at 0° and 60°, the elevation rates of the trapping efficiency were higher in the range of magnetic field intensity from 0.1 to 0.3 T compared to the values in range from 0.3 to 0.9 T. As the deflection angle was changed to 30° and 90°, the elevation rates in the range from 0.1 to 0.5 T were higher than the rates in the range from 0.5 to 0.9 T.