Research On The Cavitation Characteristics In Multi-stage Orifice Cavitator

In recent years,due to the characteristics of no pollution,low energy consumption and high efficiency of hydraulic cavitation technology,hydraulic cavitation technology has been widely used in various fields such as degradation of organic matter,preparation of biodiesel,and sewage treatment.At the same time,since hydrodynamic cavitation is a complex gas-liquid two-phase flow phenomenon,it is of great significance to study the cavitation characteristics of the flow field in the cavitator for better utilization of hydrodynamic cavitation technology.In view of this,this paper studies the cavitation characteristics of the multi-stage orifice cavitator.The research method combining numerical simulation and cavitation experiment was used to study the influence of structural parameters,flow field temperature and wall roughness on cavitation characteristics of multi-stage orifice plate cavitator.Firstly,the mechanism of hydraulic cavitation is explained and analyzed,and the process of cavitation formation,growth and collapse is studied;according to the flow velocity and pressure changes before and after the orifice plate,the flow equation and pressure loss model of the fluid in the orifice plate channel are established;At the same time,considering the conversion of gas phase(water vapor,air),the dynamic cavitation model of gas-liquid two-phase is derived to provide a theoretical basis for subsequent numerical simulations.Then,the three-dimensional model of the cavitator watershed with different structural parameters(number of cavitator stages,distance between two-stage orifice plates,number of holes,aperture,and orifice distribution)was established in UG software,and the three-dimensional model was imported into ICEM-CFD for further analysis.Structural grid division,and then import the divided grid into the fluid simulation software CFD for numerical simulation.Study the cavitation characteristics of the number of cavitator stages,the distance between the two-stage orifice plates,the aperture,the number of holes,and the orifice distribution parameters,and also consider the influence of other parameters(wall roughness,temperature)on the cavitation characteristics.By analyzing the change law of cavitation characteristics(pressure,gas holdup,turbulent kinetic energy);taking the average gas holdup and maximum gas holdup as the criteria for judging the cavitation effect,it is concluded that the above factors affect the cavitation characteristics and cavitation effect impact.Finally,the conductivity cavitation experiment was carried out to study the influence of different structural parameters(number of cavitator stages,aperture)on the cavitation effect.By measuring the conductivity of the aqueous solution after cavitation,the influence of the above parameters on the conductivity was obtained,and compared with the numerical simulation results as the evolution of the cavitation effect,the influence of the structural parameters of the cavitator on the cavitation effect was obtained comprehensively.Provide guidance for the design and practical application of multi-stage orifice cavitators.