Research On Jet And Erosion Characteristics Of A New Cavitation Nozzle

In industrial processes,efficient cleaning equipment is essential.Under the development concept of environmental protection,because chemical cleaning is not environmentally friendly,research and development of high-efficiency,low-pollution physical cleaning equipment is the development direction of related fields in the future.The cavitation jet is a new technology that combines hydraulic cavitation and high-pressure jets,and uses the energy generated by the cavitation effect to clean the surface of objects.As a carrier of cavitation,water jets generate primary cavitation through specific cavitation nozzles,and then develop into cavitation bubble clusters.The cavitation bubble groups collapse with the jets moving to the target area,and cavitation bubbles will occur when they collapse.High temperature and pressure with strong impact.However,when the cavitation jet directly enters the atmospheric environment,the cavitation effect of the jet will rapidly weaken,and the erosion energy generated by the cavitation can hardly be fully utilized.The application of cavitation jets is currently limited to submerged conditions.In view of this problem,this article will simulate and experimentally study the cavitation flow field,analyze the characteristics of the cavitation jet,develop a new type of cavitation nozzle,and improve the cavitation effect of the jet under non-submerged conditions.First,the motion equations of cavities are analyzed,the solver suitable for the simulation calculation is determined,and the preprocessing required for the numerical simulation is completed.Including the design and meshing of the physical model of the cavitation nozzle;determining the boundary conditions and parameter ranges used in the cavitation nozzle flow field;analysis of the turbulence model,multiphase flow model and cavitation model required for simulation calculation Compare.Secondly,numerical simulation was performed on the angular cavitation nozzle.The influence of various geometric parameters of the angular cavitation nozzle on the cavitation effect of the jet was analyzed by the control variable method.The simulation shows that the cavitation vortex generated when the jet passes through the throat of the angular cavitation nozzle and the liquid saturated vapor pressure region formed in the nozzle expansion section are the necessary conditions for the jet to produce the cavitation effect.Calculate the flow field of angular cavitation nozzles under non-submerged conditions,analyze the effects of different nozzle external environments and system pressure on jet cavitation effects,and verify the limitations of nozzle cavitation effects under non-submerged conditions.Then,based on the angular cavitation nozzle,the design and development of a new type of cavitation nozzle was carried out.Based on the growth process of the cavitation vortex,an auxiliary jet structure is added to the cavitation nozzle.The auxiliary jet is equivalent to extending the wall surface of the expanded section of the nozzle,so that the discrete vortices generated inside the nozzle can continue to occur in the air domain.The new cavitation nozzle flow field is simulated and calculated.Under the same parameters,the new cavitation nozzle is in the air The volume fraction of the vapor phase in the domain has been significantly improved compared to the angular cavitation nozzle.Finally,a new type of dynamic submerged cavitation nozzle is produced,and the jet characteristics and erosion test of the nozzle are tested.The jet impact force of the nozzle was measured.The test showed that the new type of dynamic submerged cavitation nozzle formed a negative pressure area near the outlet,which verified the simulation results.The cleaning test of the oil-based pen coating showed that the cavitation jet was unique compared with ordinary high-pressure jet The cleaning principle of copper plates and rusted iron plates shows that,under non-submerged conditions,the new type of dynamic submerged cavitation nozzles have enhanced jet cavitation effects compared to angled cavitation nozzles.