| Hydrocyclone is a typical equipment for separating heterogeneous mixtures.It is widely used in mineral processing,petrochemical industry,environmental protection,food,medicine and other fields.The inside of hydrocyclone is a complex three-dimensional strong swirling flow.The air core is a unique phenomenon in hydrocyclone,which has an impact on pressure drop,three-dimensional velocity and particle movement.Therefore,it is necessary to study the characteristics of air core and particle movement.In this paper,the numerical simulation method is used to simulate the flow field inside the hydrocyclone.The influence of different operating parameters on the air core is analyzed.Then the particle phase is injected into the hydrocyclone to study the particle trajectory,separation efficiency and particle turbulence intensity.Finally,the central fixed rod is added to the hydrocyclone to reduce the shadow of the air core on the particle movement and improve the separation efficiency of small particles.It is shown that the air core is the main energy dissipation area in the hydrocyclone.Different operating parameters,such as inlet liquid velocity,inlet gas-liquid ratio and material viscosity,have different effects on the flow field and the diameter of the air core.With the increase of the diameter of the air core,the energy consumption in the hydrocyclone increases,and the pressure drop also increases.Random trajectory model is used to track the particles in the hydrocyclone.Different incident points and particle sizes have different movement rules.Particles of different sizes accumulate at the top of the cyclone.The existence of air core and gas-liquid interface makes the turbulence of small particles in the central region larger.The turbulent diffusion caused by turbulent fluctuation is not conducive to the separation of small particles.Fixed rods are installed in the center of the cyclone to occupy the position of the air core.The purpose of improving the separation efficiency of small particles can be achieved.Although the 10 mm diameter central fixed rod increases the fluid flow resistance in the cyclone,but the separation efficiency of small particles is the highest.The structure is the best in this hydrocyclone by comprehensive analysis. |
