Research On Cavitation Characteristics And Influencing Factors Of Venturi Tube Type Orifice Plate

As a complex multiphase flow phenomenon,cavitation has been plaguing people because of its air corrosion,air plug and other hazards,but the high temperature and high pressure and jet effect generated by the collapse of the bubble are also gradually being valued and utilized.The enormous energy it contains can strengthen the physical and chemical reactions in the solution,making the hydrodynamic cavitation technology in sewage treatment,protein extraction and industrial production and other fields have a strong application value.Therefore,it is of great significance to study the cavitation characteristics of the cavitator and how to effectively improve its cavitation effect.In this dissertation,a new type of cavitation generating device(Venturi tube type orifice plate)is designed by combining Venturi tube with orifice plate.Taking it as the research carrier,the theoretical analysis,numerical simulation and experimental research are combined to study the influencing factors of cavitation characteristics and cavitation effect inside the venturi tube type orifice plate.Theoretical analysis: Based on the bubble growth process equation and collapse energy analysis,the bubble inception,growth and collapse region are obtained.According to the liquid flow characteristics when cavitation occurs inside the venturi tube type orifice plate,the turbulence model and multiphase flow control equation are established.Combining the macroscopic fluid mass conservation,momentum conservation and energy conservation equations with the microscopic cavitation kinematics,the water-air two-phase dynamic cavitation model and the internal gas volume fraction variation equation in the venturi tube type orifice plate are derived,which provides theoretical support for the analysis of cavitation evolution in the venturi tube type orifice plate.Numerical simulation: The three-dimensional model of the fluid domain was established in Solidworks,and the model was meshed in ICEM-CFD.The mesh surface is connected in FLUENT,and the boundary conditions are set for different structural parameters(throat diameter,throat length,inlet and outlet cone angle,hole cross-sectional area,hole arrangement,center distance,inner wall roughness and hole shape)and working conditions(inlet pressure,solution temperature).The influence of structural parameters and working conditions on the cavitation effect of Venturi tube orifice plate is analyzed by using the maximum gas volume fraction and average gas volume fraction as characterization.Experimental research: The Venturi orifice cavitation test platform was built,and hydraulic cavitation experiments were carried out on cavitation devices with different structural parameters under the same pressure.The conductivity of aqueous solution at different time nodes was measured,and the change rule of aqueous solution conductivity with time in the cavitation process and the influence rule of structural parameter change on the cavitation effect of Venturi orifice plate were obtained.In order to verify the practical application value of hydraulic cavitation,the elimination experiment of E.coli solution with Venturi perforated plates with different pore shapes was carried out.The research results provide theoretical basis and experimental reference for the application of Venturi orifice in hydraulic cavitation engineering and have important scientific significance.