Flow Field Simulation And Experimental Study Of Venturi Tube Type Hydraulic Cavitation Device

With the rapid development of the industrial economy,the problem of water pollution has become more and more serious,so the development of sewage treatment technology has attracted more and more attention.Hydraulic cavitation technology is a new type of physicochemical wastewater treatment technology.Compared with traditional chemical disinfection methods,it has the advantages of high efficiency,energy saving,no secondary pollution,and suitable for establishing large-scale industrialized wastewater treatment equipment.However,at present,hydraulic cavitation technology is still in its infancy in the field of water treatment,and there are many problems in theory and experiment.It is still at the preliminary stage of research on how to effectively generate hydraulic cavitation and what kind of efficient cavitation equipment to use.Therefore,it is of great significance to systematically study the flow field characteristics of hydraulic cavitation generators.In this paper,theoretical analysis,numerical simulation and experimental research are combined to study in depth the cavitation characteristics of the internal flow field of the venturi tube type hydraulic cavitation device under different structural parameters and working parameters.Aiming at the influence of different structural parameters on the cavitation characteristics of the internal flow field of the hydraulic cavitation device,the numerical calculation method is used to study the influence of two structural parameters,upstream slope angles and backwater slope angle of the wedge,on the flow field distribution of the steady-state cavitation field in the hydraulic cavitation device.It is found that the backwater slope angle has little influence on the flow field of hydraulic cavitation,while the upstream slope angle is the key structural parameter that affects the distribution characteristics of the internal flow field of the hydrodynamic cavitation device.The cavitation effect tends to increase with the increase of the upstream slope angle.Therefore,increasing the upstream slope angle can promote the generation of cavitation,increase the cavitation intensity,and improve the cavitation effect.Although the backwater slope angle has little effect on the cavitation intensity,the area of the cavitation region increases with the increase of the backwater slope angle.Therefore,the larger the backwater slope angle,the better the cavitation effect.Aiming at the steady cavitation field distribution inside the hydrodynamic cavitation device under different working parameters,the cavitation characteristics of the internal flow field in the hydraulic cavitation device under different inlet pressure conditions are studied by numerical calculation method in this paper.It is found that in a certain range,with the increase of the inlet pressure in the visualization experiment section,the pressure and velocity at any position inside the hydraulic cavitation flow field increase,the outlet mass flow rate increases,the cavitation period prolongs,the area of the cavitation region increases.So the cavitation intensity is enhanced and the cavitation effect is improved.Based on the steady cavitation field,the transient cavitation field inside the hydraulic cavitation device is further studied by visual experiment method.The influence of different upstream slope angles and inlet pressures on the flow field distribution characteristics of hydraulic cavitation device are discussed.The results show that the cavitation bubble group in the hydraulic cavitation device shows the trend of initiation,development and gradual collapse along with the flow downstream channel,which is an unsteady cyclical change process.Increasing the upstream slope angle will promote the generation of hydraulic cavitation,increase the cavitation intensity,prolong the cavitation period,and improve the cavitation effect.Within a certain range,the greater the inlet pressure,the wider the cavitation region,the longer the cavitation cycle,the higher the cavitation intensity,and the better the cavitation effect.