Key Parameters of Ice Particle Air Jet Ejector Structure
Ice-particle air jet surface treatment technology has the advantages of being green and harmless to the human body,and therefore,it has wide application prospects in the field of surface-material treatment.The existing ice-particle jet technology experiences difficulties,such as ice storage pellets and easy bonding,which lead to low efficiency in the surface treatment of ice-particle jets.Therefore,an efficient ice-particle air-jet injection method was proposed.Additionally,to avoid the blockage problem of ice-particle storage,a method for the instant preparation and utilization was proposed.To realize the instant utilization of ice particles and high-speed injection of ice-particle air jets,the basic structure of a jet pump was considered based on previous research,and the working and accelerating nozzles were combined by adjusting the injector structure.A working nozzle was used to suck the ice particles instantly and preliminary acceleration,whereas an accelerating nozzle was used to further accelerate the ice particles after induction to obtain a higher impact kinetic energy.Numerical simulations were performed using the coupled Fluent-EDEM method,and heat transfer was used to analyze the ice-particle ejection and acceleration laws under different structural parameters of the injector.The differences in the ice-particle ejection and acceleration performances of the working nozzle with different nozzle positions(Ld)and pressure ratios(n),and the accelerating nozzle with different diameter ratios(Dn)and length-to-diameter ratios(Ln),were investigated.The numerical simulation used the kinetic energy of ice particles as a comprehensive evaluation index,and determined the parameters of the jet structure that enabled ice particles to be utilized instantly.The simulation reached the maximum kinetic energy of the impact.Subsequently,a surface paint removal test was performed on an aluminum-alloy material using the parameters of the jet structure.The results showed that the instant utilization of ice particles and sufficient acceleration were realized.Additionally,the designed jet structure sufficiently removed paint and accelerated the surface treatment of the aluminum-alloy material.The test results showed that the designed injector structure achieved sufficient paint removal and a smoother surface on the aluminum-alloy surface,which demonstrates the scientificity and rationality of the designed structure.The simulation and test results showed that under an air pressure of 2 MPa,the nozzle parameters of the injector were n=1.5,Dn=4.0,Ld=4,and Ln=0 mm,which could sufficiently induce the accelerated ice particles,such that their kinetic energy in the ice air jet could reach its maximum value.Under the given test conditions,this jet had the best paint removal radius and surface treatment effect.The maximum paint removal radius obtained was 23 mm,and the surface roughness of the aluminum-alloy plate changed from 3.194±0.489 μm to 1.156±0.136μm.The instantaneous preparation and utilization of ice particles solve the problem of engineering applications of ice-particle air-jet technology;that is,ice-particle adhesion and storage.Additionally,it provides a new methodology in the field of material surface treatment.
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