Numerical Investigation Of The Droplet Coalescence And Breakup Behavior In Two Kinds Of Cyclone Separators

The gas-liquid cyclone separator has a wide range of applications.Increasing the separation effect of the gas-liquid cyclone separator can improve plant efficiency and reduce pollutant emissions.However,due to the condensation and fragmentation of the droplets in the swirling flow field,the particle size distribution of the droplets is changed,thereby directly or indirectly affecting the separation efficiency of the cyclone separator.Therefore,in this paper,the group equilibrium model is used to study the distribution of gas-liquid two-phase flow field,the droplet size distribution and the location of droplet coalescence in the cyclone separator.It provides a reference for the structural optimization of the gas-liquid cyclone separator.The results show that:(1)The inversion-type cyclone separator has a large tangential velocity gradient in the radial direction,large turbulent kinetic energy,and crushing of the droplets,especially in the guide vane region and the exhaust core cone.The droplets on the upper edge of the inner vane of the guide vane converge and the particle size of the droplets increases.The droplet breaks down on the windward side of the vane and causes the particle size of the droplet to decrease.The droplet breaks more severely on the windward side than on the lee side,but the vane is upwind.The average particle size of the side droplets is larger than the leeward side.(2)The presence of the short-circuit flow and the secondary flow in the collector chamber in the inversion-type cyclone separator will cause droplets to escape or back-mix.(3)The axial velocity of the gas flow in the direct flow cyclone separator is the mainstream,the flow rotation strength is weak,the gradient of the tangential velocity is small,and the axial velocity gradient,tangential velocity gradient,and turbulent kinetic energy are all smaller than that of the inversion type cyclone separator.The flow shear force is weak and the turbulent vortex energy is small enough to break the droplets.And,under the action of the wall side seams,the airflow has a more regular outward radial velocity,which causes the collision probability of the droplets to increase and the droplets to gather together clearly.The size of the windward side of the blade is much larger than that of the leeward side.As the height of the side-slit section increases along the axial direction,the droplet size of the side wall increases,and the size of the central droplet decreases continuously,which conforms to the law of gas-liquid vortex flow field.(4)The droplet breakage probability is closely related to the tangential velocity gradient,axial velocity gradient,and turbulent kinetic energy and turbulent dissipation rate.The liquid content has little effect on the droplet crushing probability,which has a great influence on the probability of droplet agglomeration.