Mechanism study and acoustic field simulation of high-energy ultrasonic vibration agitation for the preparation of cement slurry

The acoustic field calculation model of ultrasonic vibration-mixed cement slurry is established to investigate the preparation and optimization process of the slurry as well as to study the dispersion mechanism of cement particles under the action of ultrasound. The acoustic field distribution of freshly mixed cement slurry in various mixer structures at 20 kHz is calculated by using Finite Element Method (FEM) in conjunction with multi-physical field simulation. The sound field is radially spread and produces a standing wave field with sound pressure amplitude amplified close to the wall. Average sound pressure and ultrasonic effect distance at the mid-axis likewise increase as the outer diameter of the mixer bottom plate increases, and so are the positive and negative sound pressure limits in the cement slurry. The movement of cavitation bubbles can be intensified by ultrasound with a larger acoustic pressure amplitude, hence promoting the ultrasonic cavitation effect. This can be accomplished by solving the Rayleigh–Plesset equation to determine the change rule of cavitation bubbles under the effect of different acoustic pressures. The results show that the narrow space adjacent to the wall and the bottom center of the mixer arch region are the locations of the cavitation effect's core zone when the cavitation numerical simulation is utilized in conjunction with the acoustic field calculation, and the center section is lower in vertical height than the core zone along the wall. Lastly, the simulation results were verified using laser vibrometer combined with acoustic-structural coupling relations.