Abstract: In order to effectively solve the problems of fine particles agglomeration and grinding limit in mechanical large-scale powder preparation, the fine particles preparation method was adopted by cavitating jet impacts combined with grinding. The effective impact of the near-ball wall cavitating jet on particle crushing was studied. Based on the theoretical analysis of the impact characteristics of near-ball wall bubble collapse on fine particles, the effective dimensionless distance and the maximum radius of the critical bubble were obtained. Numerical simulation of the impact of cavitating jets on the spherical wall was performed, and the influences of the nozzle inlet pressures and the target distances on the distribution of near-ball wall cavities were analyzed. In order to verify the theoretical and numerical analysis results, a series of quartz sand crushing comparison experiments were carried out based on multiple factors such as target distance, rotation rate, particle mass fraction, and number of nozzles. The experimental results are in good agreement with the theoretical and numerical analysis ones, which proves the effectiveness of this method. The results show that crushing rate of fine particles in cavitation impact combined with grinding is higher than that of single grinding. Under the cavitation jet inlet pressure of 5 MPa, target distance and rotation rate are the main factors affecting the crushing effectiveness of quartz sand fine particles, followed by number of nozzles.

Key words: cavitating jet, near-ball wall, bubble collapse, fine particle crushing, particle size distribution

摘要： 为有效解决大规模机械粉体制备中存在的微细颗粒团聚和粉磨极限等问题，采用了空化射流冲击结合磨介研磨的微细颗粒制备方法，并对近球壁空化射流有效冲击破碎颗粒开展了研究。理论分析了近球壁空泡溃灭对微细颗粒的冲击特性，得出了颗粒冲击破碎的有效量纲一距离及临界空泡最大半径；通过空化射流冲击球壁的数值模拟仿真，分析了喷嘴入口压力和靶距对近球壁空泡分布的影响。为验证理论与数值分析结果，开展了基于靶距、转速率、颗粒质量分数和喷嘴数目等多因素的石英砂球磨空化破碎对比实验，实验结果与理论和数值分析结果吻合良好，验证了此方法的有效性。研究结果表明：空化冲击结合磨介研磨微细颗粒的破碎率比单一研磨微细颗粒的破碎率更高；在空化射流入口压力5 MPa下，靶距和转速率是石英砂微细颗粒破碎效果的主要影响因素，其次是喷嘴数目。

关键词: 空化射流, 近球壁, 空泡溃灭, 微细颗粒破碎, 粒度分布