溢流管直径对旋流器流场和分离影响研究

利用RSM雷诺应力模型和VOF多相流模型，系统考察了溢流管直径对Φ50 mm水力旋流器流场稳定性的影响。通过对空气柱、零速包络面、短路流及湍流强度等流场特性的分析，确定了使流场稳定的最佳溢流管直径范围，并通过旋流分离物理试验进一步验证了该溢流管直径条件下获得的稳定流场能有效提高分离效率。研究结果表明，当溢流管直径过小时，空气柱会发生中断甚至不能完整形成，分选空间内部湍流强度较高，底流分流比较大，短路流量较小。随着溢流管直径的增加，逐渐形成上下贯通的空气柱，分选空间内部湍流强度降低，零速包络面的对称性增强，底流分流比逐渐降低，流场稳定性增强，从而分离性能增强。随着溢流管直径进一步增加，空气柱直径增大，短路流量增加，流场稳定性降低，从而分离效率下降。因此，针对所考察的Φ50 mm水力旋流器最佳的溢流管直径在0.30 D左右。 

Study on Influence of Vortex Finder Diameter on Flow Field and Separation Performance of Hydrocyclone

By using RSM (Reynolds stress model) turbulence model and VOF (volume of fluid) multi-phase flow model, systematic numerical studies on the influence of vortex finder diameter on steady flow field of Φ50 mm hydrocyclone were investigated. The flow characteristics were analyzed in terms of air core, LZVV, short circuit flow and turbulence intensity. Further the range of vortex finder diameter was determined for steady flow field of hydrocyclone. Based on the physical experiments verification, the steady flow field optimized improved the separation efficiency. Results show that when the vortex finder diameter is too small, the air core cannot form completely, the turbulence intensity in the separation space is higher, the flow divertion ratio is large and the short circuit flow is smaller. With the increasing of the vortex finder diameter, the air core is gradually developing, the turbulence intensity reduces, the symmetry of LZVV is gradually enhancing and the flow divertion ratio is gradually reducing. Thus, the flow field stability and the separation performance are enhanced. With further increasing of the vortex finder diameter, the air core diameter and the short circuit flow increase, the stability of the flow field decreases inversely, consequently, the separation efficiency decreases. Therefore, a compromised optimum vortex finder diameter for the Φ50 mm hydrocyclone is around 0.30 D.