Numerical Simulation Of Cyclone Separation Characteristics Of Particles In Microgravity

In recent years,with the rapid development of China's space industry.It is urgent to explore the related theory and equipment of mineral separation under microgravity.Hydrocyclone,as an important coal separation equipment in China,relies on strong centrifugal force to hydrocyclone separation of minerals,which requires low gravity conditions.Therefore,this paper selects hydrocyclone equipment,uses computer fluid dynamics to simulate the flow field under different gravity conditions inside the hydrocyclone,and then adds particles to calculate the separation effect of the hydrocyclone under different conditions.The main conclusions are as follows:(1)With the change of gravity value,the internal pressure,tangent velocity,axis velocity and other parameters of the hydrocyclone show an incomplete symmetrical relationship,and the low-pressure air column appears in the center of the hydrocyclone,and the low-pressure area will swing from side to side along with the axis of the hydrocyclone.The characteristics of the hydrocyclone flow field change little when the gravity value changes little.With the increase of gravity value,the pressure,tangential velocity and turbulent kinetic energy of the flow field in the hydrocyclone increase,but the axial velocity and radial velocity of the fluid in the hydrocyclone have little influence.(2)In the gravity of hydrocyclone was 9.8 m/s~2 and microgravity conditions the same density under different graded the movement simulation of particles and the same particle size under the different density of particle motion simulation,that with the increase of particle diameter,normal gravity is placed under the condition of the grade efficiency of hydrocyclone has been increasing,when the particle diameter greater than 5 mm,hydrocyclone grade efficiency reached 100%;Under the other three conditions,the maximum particle size efficiency of the hydrocyclone is about70%,and the corresponding particle size is 0.5mm.(3)Although the hydrocyclone mainly relies on centrifugal force for sorting,the gravity on the direction of particle movement will affect the trajectory of particle movement.When the particle size is less than 0.5mm and the density is the same,the hydrocyclone can be classified under the conditions of positive and negative gravity,horizontal gravity and microgravity,but the classification effect is the best when the conventional gravity is placed forward.When the particle size is the same and the density is different,the movement direction of the particle is not affected by gravity,so the density has little influence on the separation effect of the hydrocyclone.(4)When the hydrocyclone is working,the gravity received by the particle in the direction of movement will increase the tangential velocity of the particle at the exit and decrease the axial velocity of the particle at the exit.(5)When the hydrocyclone is placed at 90°,it can play a good separation effect on both particle size and density grade.When the hydrocyclone is placed at 0°,the particles with different densities and particle sizes can be sorted under certain conditions,but the effect is poor.When the hydrocyclone is placed at-90°,it can classify particles according to size under certain conditions,but it has the opposite separation effect for particles with different densities.In the presence of gravity field,when the hydrocyclone is placed at 90°or-90°,the swirl in the cavity is always upward,while the outer swirl is moving downward.Therefore,when the hydrocyclone is placed at-90°,there are more low-density particles in the bottom flow port.The results are consistent with the simulation results.Combined with the simulation and experimental results,the hydrocyclone can be used as a separator to classify mineral particles under microgravity conditions,but the separation effect according to density is poor.There are 40 figures,12 tables and 98 references in the thesis.