Abstract: The performances of centrifugal extractors are mainly studied using Computational Fluid Dynamics(CFD) method,which provides certain evaluation of the flow field;however,the flow field in the centrifugal extractor cylinder,especially the influences of the inlet radius on separation effect is rarely reported. In order to solve this problem,the Particle Image Velocimetry(PIV) technology was used to analyze the internal flow field in the centrifugal extractor cylinder. A specially designed cylinder with the entrance radii of 7mm,10mm and 13mm,was tested using PIV to observe the flow field changes at different cross sections. The results showed that the fluid speed increased with the increase of cylinder radius in the terrestrial reference frame and vortex can be formed in the each separating cavity when the cylinder was taken as the reference frame. It was also found that when the entrance radius was10mm,the absolute value of the tangential velocity at each section was the highest among the tested radii and the liquid was more easily to flow towards the cylinder wall with a better separating effect. When the radial velocity relative to the rotary cylinder was positive,it was often the maximum relative velocity,indicating that the liquid passing the cylinder entrance can be thrown to the side wall,resulting in better separation.

Key words: centrifugation, extractor, entrance radius, flow field, PIV

摘要： 目前,对离心萃取器的研究多采用计算流体力学方法,为定性研究;对其转筒区域的流场研究,特别是入口半径对分离效果的影响少有报道.为了解决一问题,本文采用了PIV技术对离心萃取器转筒内部流场进行测试,使用自制转筒,分别在转筒入口半径为7mm、10mm和13mm时,观察筒内距离转筒入口11mm处截面上的流场变化规律.研究发现:以地面为参考系时,流体的转速随着转筒半径的增大而增大,而以转筒为参考系时,在每个分离腔内都能形成涡流;当入口半径为10mm时,截面内切向速度绝对值比入口半径为7mm和13mm的要大,液体更容易流向转筒边壁,分离效果更好,同时其径向速度相对于转筒为正值时,基本处于最大值,说明液体进入转筒入口后能快速被甩至边壁处,更加有利于分离.

关键词: 离心分离, 萃取器, 入口半径, 流场, 粒子图像测速