Free Sink Vortex Ekman Suction-Extraction Evolution Mechanism And Experimental Research

The suction-extraction phenomenon occurs in the formation process of free sink vortex(bathtub vortex),and it is a complex gas-liquid coupling matter.The Ekman layer coupling and its evolution mechanism involved in the above matter are a key issue with important scientific value.To address the above issue,free sink vortex Ekman suction-extraction evolution mechanism and its experimental research are carried out.The main contents involved are shown as follows:(1)Based on the multiphase volume of fluid(VOF)model and turbulent kinetic energy-dissipation(k-?)model,a two-phase fluid dynamic model oriented to free sink vortex Ekman suction-extraction was set up.Referring to the above model,the internal relations of initial rotation velocity component,drainage capacity and Ekman suction-extraction were researched,and the corresponding flow field profile regularities were revealed.The results show that if the initial velocity disturbances are variable,the heights of suction/extraction holes to container bottom keep constant;if the initial disturbances are enhanced,the rotation velocity of suction stage increases,and the suction-extraction height and Ekman layer thickness become larger,but the Ekman suction-extraction intensities of three stages including suction,extraction and penetration grow weaker;if the initial disturbances are invariable,the height of Ekman suction-extraction remains unchanged,and has no relations to drainage capacity.(2)By using the finite element method(FEM)and discrete element method(DEM)coupling calculation method,the CFD-EDEM model of the two-phase sink vortex Ekman suction volume process was established.Based on the above model,two-phase coupling dynamic characteristics and its flow field distribution in the formation process of free sink vortex were researched.Results show that before the process of liquid-solid two-phase sink vortex Ekman extracting particles to be suction-extraction stage,the movement law of liquid-solid two-phase is the same as gas-liquid two-phase.If the stage is happened,Ekman suction-extraction drag force is existed and it changes by the particles in the different vortex core positions.(3)An observation experimental platform for free sink vortex Ekman suction-extraction evolution process was set up by particle image velocimety(PIV)technology.According to the conclusion made by theoretical research,corresponding observation experiments was carried out,and it verified the correctness of model and solution method built by the article.The results above can offer important practical significance on sink vortex active control for metallurgical vessel casting,chemical extraction separation,water conservancy project status monitoring etc.