Numerical study of the synergistic effect of cavitation and micro-abrasive particles

Abstract

In ultrasonic-assisted machining, the synergistic effect of the cavitation effect and micro-abrasive particles plays a crucial role. Studies have focused on the investigation of the micro-abrasive particles, cavitation micro-jets, and cavitation shock waves either individually or in pairs. To investigate the synergy of shock waves and micro-jets generated by cavitation with micro-abrasive particles in ultrasonic-assisted machining, the continuous control equations of a cavitation bubble, shock wave, micro-jet, and micro-abrasive particle influenced by the dimensionless amount (R/R₀), a particle size-velocity-pressure model of the micro-abrasive particle was established. The effects of ultrasonic frequency, sound pressure amplitude, and changes in particle size on micro-abrasive particle velocity and pressure were numerically simulated. At an ultrasonic frequency of 20 kHz and ultrasonic sound pressure of 0.1125 MPa, a smooth spherical SiO₂ micro-abrasive particle (size = 5 µm) was obtained, with a maximum velocity of 190.3-209.4 m/s and pressure of 79.69-89.41 MPa. The results show that in the range of 5-50 μm, smaller particle sizes of the micro-abrasive particles led to greater velocity and pressure. The shock waves, micro-jets, and micro-abrasive particles were all positively affected by the dimensionless amount (R/R₀) of cavitation bubble collapse, the larger the dimensionless quantity, the faster their velocity and the higher their pressure.

Keywords: Micro-abrasive particle; Micro-jet; Pressure; Shock wave; Ultrasonic cavitation; Velocity.

Fig. 1

Illustration of the interaction between cavitation effect and micro-abrasive particles.

Fig. 2

Numerical simulation results obtained according to the initial environmental conditions in Table 1. (a) Simulation result of bubble oscillation; (b) and (c) simulation results of the velocity–pressure of the shock wave and the micro-jet, respectively, concerning the dimensionless amount of bubble collapse; (d) particle velocity and impact pressure results induced by the shock wave and the micro-jet.

Fig. 3

Simulation results for different ultrasound frequencies.

Fig. 4

Simulation results for different ultrasound sound pressure conditions. (a) Oscillation of the vacuole at sound pressure amplitude P_a = 0.0375 MP, 0.075 MPa and 0.1125 MPa; (b) and (c) simulation results of the velocity–pressure of the shock wave and micro-jet, respectively, for the maximum value of R/R₀.

Fig. 5

(a) and (b) Particle size-velocity simulation results of the micro-abrasive particle induced by the force of shock wave and micro-jet, respectively. (c) and (d) Particle size-pressure simulation results of the micro-abrasive particle induced by the force of shock wave and micro-jet, respectively.