摘要
抗空蚀材料的应用极大提高了泄水建筑物的过流性能和使用寿命,是减轻空蚀破坏最有效途径之一。针对目前关于弹性材料抗空蚀特性的机理研究尚有欠缺的问题,为了研究弹性材料如何减免空蚀破坏并探索潜在的弹性抗空蚀材料,着眼于细观层面的空化泡和弹性材料相互作用,通过低压直流放电诱发空化泡试验,研究了拉伸弹性模量范围和压缩弹性模量范围分别为0.3~9.7 MPa、0.4~7.5 MPa的弹性边界附近空化泡迁移和周期特性。结果表明:(1)弹性边界表面会随着空化泡收缩出现不同程度的隆起变形,从而弱化了空化泡的趋壁效应,并且空化泡伴随有一定程度的迁移运动。通过定量分析不同弹性边界附近空化泡的迁移量随时间变化过程,发现空化泡迁移过程主要体现在收缩-二次膨胀期间。当空化泡与弹性边界的间距一定时,随着边界材料弹性模量的降低,空化泡的迁移量和迁移速度下降。进一步建立了无量纲最大迁移距离和无量纲拉伸弹性模量的关系式,可以预测空化泡在特定弹性模量的弹性边界附近的迁移特性。(2)弹性边界可以显著影响空化泡的收缩周期,不同弹性边界条件下,空化泡收缩阶段标准化周期有不同程度的延长。对于特定弹性模量的弹性边界,大部分空化泡的标准化周期随无量纲距离的增大而减小。弹性边界的存在会减弱空化泡溃灭强度,在泄水建筑物边壁运用弹性材料可能会有利于减免空蚀破坏。研究结论可为减免空蚀破坏的应对措施提供一定的理论支持。
The application of cavitation resistant materials has greatly improved the service life of discharge structures, and is one of the most effective ways to reduce cavitation erosion. Aiming at the problem of lack of the study on the mechanism of the anti-cavitation characteristics of elastic materials and in order to study how to reduce cavitation damage by elastic materials and explore potential elastic anti-cavitation materials, the migration and periodic characteristics of the cavitation bubbles with the range of the tensile elastic modulus and the range of compressive elastic modulus of 0.3~9.7 MPa and 0.4~7.5 MPa near elastic boundary are studied herein with a view to the interaction between cavitation bubbles and elastic materials at the meso-level through the experiment of cavitation bubble induced by low voltage DC discharge. The study results show that(1) the elastic boundary surface is to be bulged and deformed to various degrees with the contraction of cavitation bubble, thus the wall-effect of cavitation bubble is to be weakened with the migration of the cavitation bubble to a certain extent. Through quantitative analysis on the time-dependent changing processes of the migrations of cavitation bubbles near various elastic boundaries, it is found out that the migration process of cavitation bubble is mainly embodied in the contraction — secondary expansion period. When the spacing between the cavitation bubble and the elastic boundary is constant, the migration and its speed of cavitation bubble are decreased along with the decrease of the elastic modulus of the boundary material. And then, the relationship between dimensionless maximum migration distance and dimensionless tensile-elastic modulus is further established, thus the migration characteristics of the cavitation bubbles near the elastic boundary with specific elastic modulus can be predicted;(2) the contraction period of cavitation bubble can be significantly affected by the elastic boundary, and then the standardized period of cavitation bubble contraction stage is to be prolonged to various extents under different elastic boundary conditions. Most of the standardized periods of the cavitation bubble contraction stages are to be decreased along with the increase of the dimensionless distance for the elastic boundary with specific elastic modulus. The existence of elastic boundary can weaken the collapse intensity of cavitation bubble, thus the application of elastic material to the side wall of water discharge structure can be favorable to reduce and avoid cavitation damage. The study conclusion can provide a certain theoretical support for the countermeasures to reduce and avoid cavitation damage.
作者
翟俨伟
刘志武
李健薄
ZHAI Yanwei;LIU Zhiwu;LI Jianbo(China Three Gorges Corporation,Beijing 100038,China;State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610065,Sichuan,China;National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Hohai University,Nanjing 210098,Jiangsu,China)
出处
《水利水电技术（中英文）》
北大核心
2022年第3期91-109,共19页
Water Resources and Hydropower Engineering
基金
国家自然科学基金青年基金项目(52109081)。
关键词
空化泡
弹性边界
迁移
周期
试验研究
水力特性
水电站
影响因素
cavitation bubble
elastic boundary
migration
period
experimental study
hydraulic characteristics
hydropower station
influence factor
