Research On A New Type Runoff Hydrodynamic Vortex Separator By Experiments And Simulation

Storm runoff pollution has become one of the most important links which caused urban environment pressure for the past few years.Because of the large radial flow and deficient stability of pollution load,the application of traditional biochemical technology is limited.However,the hydrodynamic vortex separation technology,which had the characteristics of fast storm water separation and high efficiency,has been developed rapidly.Based on a new type of hydrodynamic vortex separation technology,the experimental method and Computational Fluid Dynamics(CFD)technology were used to study the designing,improvement and application of this technology.According to the fundamental and foreign engineering practice of the hydrodynamic vortex separation technology,we preliminarily designed the separator.The most important step in this process was the designing of internal structure.The inner vortex,outer vortex and sedimentary area which ensure the basic function of separator,play an important role in the retention and precipitation of particles.According to the influence of the separation efficiency,the main designing parameters were the height of the inlet,the horizontal angle of inlet,the outlet type and the inner tube design.Simulation results and experimental study showed that the increasing of inner cone angle and tangential,could significantly improve the processing efficiency of separator.The relationship among design optimization,controlling parameters and separation efficiency was researched by experimental method and CFD simulation.This provided support for designing,controlling and engineering of the technology.According to the study of removal efficiency,Relative Percent Difference(RPD)between numerical simulation and experimental results was within 10%.The results of numerical simulation could effectively reflect the separation process.Among the three main operating parameters,particle size and water flow were the main factors which influenced the efficiency of hydrodynamic vortex separation.Hydrodynamic vortex separator has better separation effect for larger particles.For the study of single factor,the increasing of the inlet flow rate would reduce the separation efficiency of separator as the decrease of residence time.The hydrodynamic vortex separator had a high efficiency of separation,and could achieve nearly 100% efficiency for light floating objects.The simulation and experiment showed that the separator could completely trap the particles of more than 200 ?m.For particles below 10 ?m,the efficiency was reduced to less than 10%.The method of artificial simulated rainfall were used to reflect the separation efficiency of the separator in practical application.In this experiment,SS reached 41% cumulative reduction in 5 minutes,and particles larger than 100 ?m were effectively trapped.Other pollutants removal efficiency largely depend on its existing state.Cumulative reduction of COD was 42% respectively in 5 minutes.