Sound Field Simulation Analysis And Experiment Of Ultrasonic Stirring Magnetorheological Polishing Liquid

Magnetorheological polishing fluid is a new type of intelligent material whose rheological properties can be changed.It is widely used in the finishing of precision parts and brittle and hard materials.However,the sedimentation of particles during storage affects the processing efficiency and service life..Ultrasonic agitation utilizes the ultrasonic cavitation effect.The local high temperature and high pressure generated when the cavitation bubbles collapse in the liquid,and the magnetic rheological polishing liquid is efficiently stirred at the molecular level with the acoustic rush flow to improve the stability of settlement.Various factors such as sound source conditions and liquid medium parameters affect the ultrasonic cavitation field.In view of the current situation of insufficient sound field research in the mixing process,this paper uses multiphysics numerical calculation method to analyze the influence of multiple process parameters on the distribution and evolution of ultrasonic stirring sound field.Then select appropriate process parameters to optimize the preparation process of magnetorheological polishing fluid.The main research contents are as follows:(1)The domestic and foreign research progress of ultrasonic cavitation field and magnetorheological polishing fluid are reviewed.It is proposed that ultrasonic assisted stirring of magnetorheological polishing fluid can improve the preparation efficiency,reduce particle cohesion,and slow down particle sedimentation.(2)Based on the basic principles of linear acoustics,combined with the coupling of acoustic piezoelectricity and acoustic structure,an acoustic field simulation model of ultrasonic stirring magnetorheological polishing fluid is established.The liquid medium is a porous medium wood model,which is analyzed in the frequency domain under steady state.(3)Based on the sound field simulation model,the sound field distribution of the magnetorheological polishing fluid under different penetration depths,different frequencies and different powers of the ultrasonic horn is numerically simulated.The results show that as the distance from the sound source increases in the sound field,the sound intensity gradually decreases,and the high sound intensity area is mainly distributed in the direction of the axis of the output end of the horn.The sound intensity decreases rapidly exponentially within 20 mm from the horn,and the sound pressure fluctuates on the axis.The best penetration depth of the horn is 10 mm,and the overall axial sound intensity is the largest.The higher the power,the greater the sound pressure value everywhere,and the expansion of the sound pressure isosurface contributes to the expansion of the cavitation area.Increasing the frequency makes the sound beam more concentrated,and lateral standing waves appear near the wall surface.Too high a frequency hinders the collapse of cavitation bubbles and reduces the cavitation effect.The effect of particle content on the sound pressure distribution is studied.The results show that the sound pressure decay rate is faster when the particle volume fraction is high,mainly due to the increase of the liquid viscosity coefficient,the ultrasonic energy is absorbed more.(4)The effects of changes in length and radius on the sound field distribution in different containers are studied.Reducing the radius of the container is conducive to the generation of maximum sound pressure.When the container radius is the same,the change of the container height makes the maximum sound pressure value fluctuate,which is due to the occurrence of standing waves or resonance phenomena in containers of different heights.Based on the empirical formulas of sound intensity and flow velocity,the distribution of flow velocity at different penetration depths is simulated.The increase of penetration depth decreases the maximum flow velocity.As the penetration depth increases,the vortex moves to the liquid surface.Changing the shape of the container and analyzing the flow field distribution of the conical container at different heights,the results show that the vortex range of the conical container is wider than that of the cylindrical container,and the radius is unchanged.expand.The maximum flow velocity at the bottom of the conical container with a height of 60 mm is3.24cm/s.(5)The sound intensity measurement instrument was used to measure the sound intensity in different horizontal and vertical directions in the magnetorheological polishing fluid,and the simulation results of the sound field were verified.The simulation results are basically consistent with the experimental measurement results.Because the sound waves are reflected on the bottom to form a superposition,the sound intensity at the bottom increases to a certain extent.Using cavitation cloud photography combined with aluminum foil corrosion method to measure the strength of the sound field cavitation effect,the results show that the cavitation intensity increases with time.Increasing the ultrasonic power increases the overall sound field intensity,but excessive power increases the sound attenuation effect.The sound intensity attenuation in the horizontal direction is greater than that in the axial direction.The cavitation cloud in the water is distributed in an inverted triangle shape,and the bubble density at the end of the horn is the largest.The sound field signal waveform was measured using a hydrophone.With the increase of power,the amplitude of the voltage signal increases and the complexity of the waveform increases,resulting in highfrequency noise.