本论文设计了自制的旋转圆盘式空蚀模拟实验机，并利用其进行了大量的模拟实验，利用表面形貌仪、光学显微镜、扫描电子显微镜等仪器，采取多种观测手段进行定性分析，从多方面研究了空蚀发生机理及影响因素。分别采用不同的扰流方式进行实验，对Q235钢在不同空化条件下的空蚀结果进行比较，研究了空化对空蚀发生的影响，实验结果表明空化是空蚀的必要条件，扰流物对空化发生具有直接影响，扰流物的存在使空蚀概率大大增加。对自来水、纯净水、去离子水不同水质对空蚀的影响进行实验，考察了水质对空蚀的影响，研究结果表明空蚀的发生与水质有关，且随着水的纯净度的提高，空蚀破坏程度减小，不含颗粒的水中虽然有空化产生，但产生的空蚀破坏小。空蚀破坏程度依次为自来水、纯净水、去离子水，在去离子水中难以发生空蚀。采用7m、500nm、50nm三种不同粒径的SiC颗粒，研究了粒径对初生空蚀的影响，研究表明水中空蚀的发生与微颗粒的存在有关，空蚀程度随着粒径的增加而先增加后减少。当粒径增加到微米量级时，空蚀程度有所下降。不含颗粒的去离子水中难以发生空蚀。在去离子水中加入粒径为500nm的SiC固体颗粒，研究了不同颗粒浓度对空蚀的影响，利用扫描电子显微镜进行表面形貌分析，结果表明水中的颗粒浓度对空蚀有一定影响，空蚀程度随着水中所含颗粒浓度的增加而增加，但达到一定浓度时，对空蚀程度影响变弱。选择Q235钢作为基体材料，使用不同表面加工工艺，获得了七种不同构型的表面形貌，并在此基础上进行了表面形貌对空蚀影响的研究，研究发现表面形貌特征对于初生空蚀具有一定影响，提出可以通过表面形貌构型的优化设计来实现对空蚀的控制。空蚀程度与运行时间有关，随着时间的增长，空蚀破坏程度加剧。空蚀孕育期的破坏是瞬时形成的且破坏位置有一定随机性，破坏特征为表面塑性变形和针孔状蚀坑，而在空蚀加速期，初生空蚀坑的存在将加速材料破坏。在水中，空蚀破坏主要是气泡在近壁面坍塌造成的微激波和微射流联合作用下形成的，打击时伴有高温，使空蚀坑周围形成氧化层。使用多种分析手段对空蚀坑进行了研究，分析认为在空蚀孕育期，力学作用是造成空蚀破坏的主要原因：微气泡坍塌引起的微射流和微激波指向壁面并产生冲击波，引起表面破坏，且破坏最严重的部分在距表面一定深度下。关键词：空蚀 空化 颗粒 表面形貌

A kind of rotary disc cavitation apparatus is designed and completed in this paper, and lots of cavitation experiments are performed on this apparatus. Surface profile tester, SEM (scanning electronic microscope) and tool microscope are used to observe and analyze the surface experienced the cavitation in the apparatus. Then, the mechanism of the cavitation damage and the influencing factors are investigated based on the experiment results.The cavitation experiments on Q235 steel under different burble conditions are performed, and the experiment results are compared to study the effect of cavitation on the cavitation damage. The comparison results show that the cavitation is the necessary condition for the cavitation damage, and the turbolator obviously affects the cavitation, its existence greatly increases the probability of the cavitation.Cavitation experiments using tap water, filtered-water and de-ionized water are also performed to investigate the effect of water quality on cavitation damage. The experiment results show that the cavitation damage is decreased as the water quality is improved; although the cavitation appears when the water containing no particles is used in the experiment, the cavitation damage is minute. The damage caused by the tap water is the greatest, then the filtered-water, and the last, the de-ionized water. The cavitation damage hardly generates when the de-ionized water is used.Three different kinds of SiC particles with diameters of 7 m, 500nm and 50nm are used in the cavitation experiments to investigate the effect of particle size on cavitation damage. The experiment results show that the generation of the cavitation is related with the existence of particles, the damage level is firstly increased and then decreased as the particle size increases. when the particle size is in the order of micron, the damage decreases. The cavitation damage hardly occurs in the de-ionized water without particles.The effect of concentrations of SiC particles with 500 nm diameter in the water is investigated. With the analysis of surface roughness using SEM, it is concluded that the particle concentration in the water is related with the cavitation damage, the damage level is increases when the particle concentration increases, but its effect is weakened when the concentration reaches a certain level.The effect of surface roughness on cavitation damage is also investigated. Seven different kinds of surface roughness are machined on the Q235 basis using different machining methods. The experiment results show that the surface roughness characteristics affect the primary cavitation, and the optimum design of surface roughness can control the cavitation damage.The damage level is related with the experiment time. The damage is increased as the experiment time increases. The damage occurs instantly and the damage position is random when the cavitation damage is in incubation period. The damage characteristics are surface plastic yield and needle-like cavitation pocket. In acceleration period, the existence of the primary cavitation pocket accelerates the damage of material surface. In water, the cavitation damage is caused by the coaction of formed from the collapse of micro bubble near the wall. High temperature is generated when the cavitation pocket is formed, and the oxidizing layer are formed around the pockets.Many analysis methods are used to study the cavitation pockets. It is concluded that the mechanical effect is main factor that affects the cavitation damage; the micro shock wave and micro jet stream caused by the collapse of the micro bubbles heads the wall and form the blast wave, then the surface is damaged, and the most serious damaged part of the material is under the surface with a certain distance.Keywords:Cavitation Cavitation damage Particle Surface roughness