粗糙表面的空蚀机制研究  

On Mechanism of Cavitation Erosion of Rough Surface

作　　者：刘诗汉[1,2] 陈大融[1] 

机构地区：[1]a清华大学摩擦学国家重点实验室,北京100084 [2]空军第一航空学院,河南信阳464000

出　　处：《润滑与密封》2009年第3期6-8,35,共4页Lubrication Engineering

基　　金：国家重点基础研究发展计划项目(2007CB707702);摩擦学国家重点实验室自主课题(重点项目)

摘　　要：对2种不同表面粗糙度的45#钢进行超声振动空蚀实验,发现粗糙表面的空蚀程度(空蚀坑的数量和尺寸)比光滑表面的高。通过对空化形成条件及微射流对表面冲击过程的理论分析,指出粗糙表面比光滑表面更容易空蚀的原因是:粗糙表面的裂隙含有气核,增加了空化的几率;表面缺陷增多增加了破损的几率;表面凸起阻挡射流冲击表面后的侧向流动,延缓了冲击高压区的卸载导致蚀坑加深;侧流冲击导致凸起破断和表面撕裂。Ultrasonic vibration cavitation erosion experiments were carried out on two groups of carbon steel specimens with very different roughness. Extensive cavitation erosion was found on the rough surfaces （with more and larger pits）. Four reasons were pointed out, by analyzing the cavitation condition and the impact of microjets formed at the end of the cavity collapse, to contribute to the heavy cavitation erosion on rough surfaces：more gas nuclei contained in the gap wedges on the rough surfaces produce a high probability of cavity;more cracks on the rough surfaces means easier damaging occurrence ; rejection of slot walls to the outward radial flow formed after the micro-jet impacts the surface delays the release of the high pressure in impact center area, and hence deepens the pit;the high speed outward radial flow breaks the microridges and tears the surface material near the cavitation pit.

关 键 词：粗糙度 空蚀 初生期 微射流 

分 类 号：TH140.7[一般工业技术—材料科学与工程]