Experimental Study And CFD Simulation For Hydrocyclone Separation Of Initial Rainwater

The serious pollution of initial stormwater has become one of the main causes of urban water environment pollution.Based on the analysis of the characteristics of urban initial stormwater,the hydrocyclone separation equipment was designed according to the foreign hydrodynamic cyclone separation technology combined with the traditional hydrocyclone separation technology and particle precipitation separation.Using lab scale experiments,the removal performance of the hydrocyclone separation equipment for solid particles with different sizes was investigated.And analysed the flow field inside the equipment using Fluent software.Results showed that this hydrocyclone separation equipment could remove about 70% of solid particles with the average particle size of 140 ?m,and about 40% of solid particles with the average particle size of 80 ?m.Repeated tests on the hydrocyclone separation of particles with the average particle size of 80 ?m suggested that the hydrocyclone separation equipment had stable operation performance.This paper modeled the designed lab scale hydrocyclone separation equipment geometrically.Results showed that the swirl motion was not very well in the inner tube of hydrocyclone separation equipment.Besides,the flow rate in inner tube and outer tube was very low.The static pressure inside the equipment decreased gradually from inlet to outlet.In general,the distribution of flow field at different inlet velocities had no significant difference.Furthermore,the designed lab scale hydrocyclone separation equipment was modified and analyzed the flow field inside the equipment using Fluent software.Results showed that when inlet pipe was connected the inner tube tangentially,the swirl velocity of the fluid inside the inner tube was improved.And when increasing the height ratio of inner tube and screen,the swirl motion was more obvious in inner tube,in addition,the kinetic energy of the fluid was well attenuated.The lab scale experiments and CFD simulation showed that the optimum structure and operation parameters of this lab scale hydrocyclone separation equipment were as follows.The ratio of inner tube diameter to outer tube diameter was 2:1.The ratio of the inner tube height to the screen height was 3:1.And the HRT was 90 s.