Analysis Of The Movement Process Of Single Cavitation Bubble Under Ultrasonic Vibration Honing Considering Thermal Effect

Ultrasonic vibration honing technology as an effective means for materials that are difficult to machine,grinding fluid under the action of ultrasound will produce cavitation phenomenon.It cannot be ignored that the vibration process of cavitation bubble,the extremely high temperature and pressure physical environment of the collapse of bubbles and the resulting micro-jet and shock wave affect material surfaces.In this paper,in view of the cavitation bubble in the grinding zone,the change of some parameters in the process of single cavitation bubble is studied by means of theoretical modeling,numerical simulation and experimental analysis combining the relevant theory of cavitation bubble dynamics.In addition,the role of various factors on the motion of single cavitation bubble is explored.The main contents and conclusions of research are as follows:1.Based on previous researches,considering the characteristics of kerosene vapor condensation and evaporation and honing environment,the dynamic model of single cavitation bubble in ultrasonic vibration honing grinding area is established.By the Matlab software,it is numerically simulated that the bubble radius,temperature,pressure and kerosene vapor molecular number in the process of bubble moving.The results show that the condensation and evaporation of kerosene vapor can help to understand changes of bubble temperature and bubble pressure.2.Compared with different ultrasonic environments and initial radii,the consequences show that due to the honing pressure,the amplitude of cavitation bubble under ultrasonic vibration honing is greatly suppressed,but the rate of movement is faster.Meanwhile,the minimum value of pressure and temperature is larger,and the number of kerosene vapor molecules is less.Additionally,with the increase of the initial radius of the cavitation bubble,the time of rapid expansion of the bubble radius is advanced,the maximum expansion ratio is reduced and the compression and collapse time is correspondingly shortened.Similarly,the maximum value of the pressure and temperature in the bubble becomes larger,and the kerosene vapor molecules are more.3.The impact of ultrasonic honing and external environmental factors on the cavitation bubble motion is studied.It shows that honing pressure,kerosene liquid viscosity and ultrasonic frequency play important roles,but the rotation and reciprocating speed of honing head have little effects.The rise in honing pressure will significantly reduce the maximum radius of the cavitation bubble and may also collapse the cavitation bubble directly.As the viscosity coefficient of the liquid is greater,the resistance of the cavitation bubble expansion is higher and the change of radius is smaller.Moreover,the time of ultrasonic effect is shorter with the improvement of ultrasonic frequency.The cavitation bubble is hard to fully experience the growth process,and the radius will become smaller.4.The motion state of the bubble under diverse external sound field is discussed.By comparison with single-frequency excitation(sinusoidal signal),it is found that the cavitation bubble under multi-frequency excitation experiences a more gentle growth period.And the combination of various phase differences of multi-frequency excitation can change the vibration of cavitation bubble randomly.At the same time,opposite to the square wave,triangular wave power is weak,so the input sound field energy is also less,leading to the bubble radius being slightly smaller.5.The acoustic field of ultrasonic honing is measured by the hydrophone method.The results show that with the increase of the distance between the transducer and the horn,the measured cavitation pressure decreases gradually.Owing to the enhancement of ultrasonic generator power,sound pressure value is elevated obviously.Besides,the cavitation effect on the surface of the material is studied by using aluminum foil etching method.It indicates that aluminum foil surface will appear many different sizes of cavitation pits,and cavitation pits become denser when the ultrasonic generator power increases and the transverse distance between aluminum foil and horn reduces.The bigger the sound pressure value of the place,the more dramatic cavitation effect.