关键词: 离心分离, 萃取器, 入口半径, 流场, 粒子图像测速

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