突扩突跌布置侧墙及底板脉动压力特征分析  

Fluctuant characteristics analysis of sidewall and bottom behind sudden lateral enlargement and vertical drop form

作　　者：聂孟喜[1] 李琳琳[1] 段冰[1] 

机构地区：[1]清华大学水利水电工程系

出　　处：《清华大学学报（自然科学版）》2007年第3期331-334,339,共5页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目(50479002)

摘　　要：为进一步研究突扩突跌体型的脉动压力和空蚀破坏，用三峡泄洪深孔突扩突跌掺气水工模型对侧墙和底板的水流脉动压力进行了详细量测，建立了压力脉动强度σ与壁面剪切应力的关系式。给出了侧墙和底板脉动压力强度系数K的表达式；侧墙冲击点处脉动压强偏离正态分布，底板脉压幅值是时均压力的35％～50％。通过时间积分比尺TE和空间积分比尺Lf的分析，发现侧墙冲击点处的TE值较大，相应的Lf值也较大，冲击点下游孔和Lf很快变小，其规律与频谱分析一致。水流冲击底板处，主频带窄，脉动压力强度大，时间积分比尺值和纵向积分长度比尺也较大。Fluctuating water pressures can cause cavitation corrosion at the deep outlet of the Three Gorges Dams. These measured pressure fluctuations were measured along the sidewall and the bottom of a physical model of the dam. The results related the pressure fluctuation intensity, a, and the wall shear stress. The expression of pressure fluctuation intensity coefficient K was given. The fluctuating pressure distribution at the impact spots on the sidewall was found to differ from the expected values. The fluctuations in the pressure at the bottom wall were 35% - 50% of the time averaged pressure. Analysis of the time and space integral scales shows that time and length scales, TE and Lf, at the impact spots on the sidewall are larger than on the downstream side. The rule is consistent with the spectral characteristics. The fundamental frequencies at the impact spots on the bottom wall are less than in other areas while the pressure fluctuations, the time and space integral scales are larger than in other areas.

关 键 词：脉动压力 脉动压力强度系数 频谱特征 相关函数 

分 类 号：TV131.6[水利工程—水力学及河流动力学]