Ultrasonic-coupled Gas-liquid-solid Three Phase Abrasive Flow Field Characteristics And Regulation Method

Abrasive flow processing uses the fluid medium with abrasive particles to perform material removal for workpiece surface.Since the fluid is with the merit of geometric profiling,abrasive flow processing has apparent advantages of workpieces with complex curved surfaces or structural surfaces.In view of the characteristics of micro-force/cutting,its material removal quantity is relatively low,leading to long processing time.Therefore,how to increase the processing efficiency under the condition of high surface quality is a difficult problem in the area of abrasive flowing processing.The gas phase is drawn into the solid-liquid two-phase abrasive,the so-called gas-liquid-solid three-phase abrasive flow is formed,which can improve the internal energy and profile uniformity of abrasive flow field,and increase the processing efficiency of abrasive flow processing.Ultrasonic cavitation is a special physical phenomenon caused by the ultrasonic wave in fluid,in which the cavitation bubbles form,develop,expand and collapse in the affecting region of ultrasonic wave.Related research works suggested that the ultrasonic cavitation bubbles posses the high-temperature/pressure energy,which release instantly by the cavitation bubble collapsing,expand with the approaches of shock wave and micro-jet,and cause remarkable influence to the motion states of periphery abrasive particles.Accordingly,this paper introduces the ultrasonic cavitation into abrasive flow processing area,and proposes a ultrasonic coupled gas-liquid-solid three-phase abrasive flow processing method,which uses the ultrasonic cavitation effects to improve the material removal rate of abrasive flow processing and increase the processing efficiency and surface quality.Regarding the above research objective,this paper performs the resech works by the following contents.(1)Considering the technical characteristics of gas-liquid-solid three-phase abrasive flow processing,based on the theories of gas-liquid-solid multi-phase flow and turbulent flow,in combination with the improved Preston equation,a fluid mechanic model for gas-liquid-solid three-phase abrasive flow processing is set up,the flow field profiles of velocity vector,dynamical pressure and turbulent kinetic energy in a constrained flow passage involved by the processing procedures are acquired,and the affecting mechanism between the abrasive-wall colliding kinetic energy and cutting efficiency is obtained.(2)According to the fluid ultrasonic cavitation theory,the affecting regularities for ultrasonic cavitation process and abrasive flow motion are researched,and a dynamic model for ultrasonic coupled gas-liquid-solid three-phase flow flied enhancing is set up.By the Rung-Kutta method,the improved Rayleigh-plesset equation is resolved to obtain the conditions of temperature and pressure of ultrasonic cavitation in the transmission process.Based on the computation results of the cavitation pressure in abrasive flow,a theoretical model for the affecting mechanism between the micro-bubble collapsing and abrasive particle kinetic energy is developed to obtain the gained kinetic energy of abrasive particle caused by the micro-bubble collapsing.Subsequently,the influencing law for the processing effects owing to the micro-bubble evolution process is revealed.(3)To address the regulating matter of shock wave and micro-jet created by the cavitation micro-bubble collapsing,an inverter control method oriented to the gas-liquid-solid three-phase fluid abrasive flow processing is put forward.Referring to the control method,an ultrasonic wave generation apparatus for gas-liquid-solid three-phase fluid abrasive flow processing is designed.Based on the above experimental apparatus,the energy released by the micro-bubble collapsing process can transmit into fluid shock wave in a small fluid volume entity,and the cavitation shock in the three-phase fluid abrasive flow can be excited.Consequently,the particle velocity is increased,the turbulence intensity is enhanced,the affecting force of particle-wall becomes higher,and the processing efficiency of abrasive flow will be improved.(4)The observation and processing experimental platforms for the gas-liquid-solid three-phase abrasive flow processing are established,and the three-phase abrasive flow processing experiments under the condition of ultrasonic coupling are finished.Taking the silicon slices as the processing objects,according to the removal states of the surface oxide layer,the enhancing effects for the silicon surface material removal by the ultrasonic cavitation are analyzed.According to the experiment results of ultrasonic coupled three-phase abrasive flow processing,the influencing regularities for cutting effects of abrasive flow by ultrasonic cavitation are observed.The experiment results showed that the proposed method can improve the internal energy of abrasive flow,and increase the cutting efficiency and surface quality of gas-liquid-solid three-phase abrasive flow processing.