溢流管壁厚对旋流器内部流场和分级性能的影响

Effect of Overflow Pipe Wall Thickness on the Internal Flow Field and Classification Performance of a Hydrocyclone

水力旋流器是一种将压力能转化为动能的设备,因其独特的分选优势被广泛应用于各类分选行业中,但旋流器由于其自身结构的限制,导致旋流器分级精度较低,其中,结构参数是影响旋流器分级性能高低的重要因素之一,溢流管壁厚作为旋流器的参数之一,对分级精度有着较大影响,但溢流管壁厚对旋流器分级机理的影响未见详细报道。因此,本文运用流体动力学手段呈现了压力场、速度场和分级效率随溢流管壁厚的变化规律,量化了其内部流场的变化特征。结果表明,随着溢流管壁厚的增加,短路流量大幅降低,这是由于溢流管壁厚的增加延长了短路流进入溢流管底端的距离,在运动过程中被外旋流或内旋流重新卷吸到预定分离区域,参与正常分级,极大减小了错位粒子的数量。径向速度随着溢流管壁厚的增加而增加,这使得粗细颗粒快速形成粒度层,减少了细颗粒进入外旋流的概率。对于直径75 mm的旋流器,随着溢流管壁厚的增加,切割粒径呈现出先减小后增加的趋势,当溢流管壁厚为10 mm时,切割粒径为17.2μm。分级精度随着溢流管壁厚的增加逐渐提高,当溢流管壁厚为15 mm时,陡度指数为0.68,因此,采用厚壁溢流管结构可以提高旋流器切割能力同时有效提高旋流器的分级精度,得到的数据为新型旋流器的设计提供了理论依据和数据支持。

Hydrocyclone is a device that converts pressure energy into kinetic energy.Due to its unique sorting advantages,it is widely used in various sorting industries.However,due to the limitations of its own structure,the classification accuracy of the cyclone is low.Among them,structural parameters are one of the important factors affecting the classification performance of the cyclone,and the wall thickness of the overflow pipe,as one of the parameters of the cyclone,has a significant impact on the classification accuracy.However,the impact of the wall thickness of the overflow pipe on the classification mechanism of the cyclone has not been reported in detail.Therefore,this study used fluid dynamics methods to present the changes in pressure field,velocity field,and classification efficiency with the wall thickness of the overflow pipe,quantifying the characteristics of the internal flow field.The results show that as the wall thickness of the overflow pipe increases,the short-circuit flow rate significantly decreases.This is because the increase in wall thickness of the overflow pipe extends the distance of shortcircuit flow entering the bottom of the overflow pipe,and is re-sucked into the predetermined separation area by external or internal swirls during movement,participating in normal classification and greatly reducing the number of misaligned particles.The radial velocity increases with the increase of the overflow pipe wall thickness,which causes coarse and fine particles to quickly form a particle size layer,reducing the probability of fine particles entering the outer vortex.For a 75 mm diameter cyclone,as the wall thickness of the overflow pipe increases,the cutting particle size shows a trend of first decreasing and then increasing.When the wall thickness of the overflow pipe is 10 mm,the cutting particle size is 17.2μm.The classification accuracy gradually improves as the wall thickness of the overflow pipe increases.When the wall thickness of the overflow pipe is 15 mm,the steepness index is 0.68.Therefore,using a thick wall overflow pipe structure can improve the cutting ability of the cyclone and effectively improve the classification accuracy of the cyclone.The obtained data provides theoretical basis and data support for the design of new cyclone.