Study On The Internal Flow Field Of Three Products Hydro-Cyclone Screen Based On Conical Screen

The three products hydro-cyclone screen has significant effect on the improvement of the fine-grained coal classification performance,which has extremely important research significance.In previous studies,the existence of conical screen in the cone section is rarely involved,which is the important area where particles are separated.Therefore,it's particularly important to systematically study the three products hydrocyclone screen based on conical screen.It provides some help for the following structural optimization and practical application.This thesis first introduces the development history,research progress and working principle of three products hydro-cyclone screen,and briefly summarizes the influence of structural parameters on the classification performance.Then studied the fluid behaviour and the force of particles based on the theory of rotating flow and the theory of particle screening,the theoretical distribution rules of pressure and velocity are obtained.And pointed out that the tangential velocity of fluid is the key to research.Firstly,the SolidWorks was used to simplify the model of three products hydrocyclone screen,then the geometric model was meshed by ICEM CFD.Finally,using the Fluent software,the turbulence was calculated by using Reynolds stress model(RSM)and the gas-liquid two phase was calculated by using volume of fulid model(VOF).After the calculation results convergent,the internal flow field information is obtained.The distribution of internal pressure and velocity in the three products hydrocyclone screen was studied.Compared the difference of flow field between it and cyclone,then pointed out that the behaviour of inner vortex is mostly influenced by screen,the flow and pressure dorp were compared subsequently.The influences of inlet velocity,cylindrical section height,number of screen,screen position,cross-sectional area of screen underflow outlet and the chamber width on internal flow field were investigated in depth,and the variation trend of static pressure,axial velocity and tangential velocity and flow distribution were obtained.Numerical simulation shows that the inlet velocity only changes the numerical value and does not affect the laws.The tangential velocity can be increased by reducing the height of cylindrical section.The change of flow field gradually flattens with the increase of the number of screen.The position of the screen has a significant effect on the inner vortex.The corsssectional area of the screen underflow outlet affects the static pressure of the fluid when through the screen.The width of the chamber has a limited effect on the internal flow field,but it has a significant effect on the screen underflow behaviour.Therefore,a structure with the same cross-sectional area of the screen underflow is designed(equal chamber width,ECW),which has a significant effect on the reducing the static pressure in the chamber and can weaken the backflow phenomenon.Finally,researched the influence of double feeding,the length of screen underflow outlet,the center occupied by the solid core,and the screen with different aperture ratio in axial height on the fluid behaviour.The double feeding model is helpful to the symmetry of the flow field and can reduce the local turbulence.Prolonging the outlet pipe can reduce the negative pressure,and has no significant effect on the internal flow field.And the conclusion is opposite to the cyclone when add the solid core.Reducing the aperture ratio of middle and lower regions of the screen has little effect on improving the tangential velocity of the inner side of the screen.There are 94 figures,18 tables and 81 references in thesis.