前置掺气坎高度对阶梯溢流坝水力特性的影响  

Experimental Investigation on the Influence of Height Variations of the Pre-Aerator to the Hydraulic Characteristics of the Flow in the Stepped Spillways

作　　者：朱利[1] 张法星[1] 刘善均[1] 

机构地区：[1]四川大学水力学与山区河流开发保护国家重点实验室,四川成都610065

出　　处：《人民黄河》2014年第6期110-112,共3页Yellow River

基　　金：国家自然科学基金资助项目(51109150)

摘　　要：将掺气坎设置于阶梯溢流坝闸墩出口处,有利于阶梯掺气,避免阶梯空蚀空化。通过1∶25模型试验,在宽尾墩阶梯溢流坝上设置不同体形的前置掺气坎,研究了掺气坎高度变化对坎后有效空腔长度、空腔最大高度、下游坝面掺气浓度沿程分布、水舌冲击力大小的影响,并与未设掺气坎体形时对应的水力学参数进行了对比分析。结果表明:与未设掺气坎相比,增设掺气坎后阶梯沿程掺气浓度增长明显;有效空腔长度随坎高的增大而增大,空腔最大高度随坎高的增加无明显变化;随着坎高增加,水舌冲击力相应增加,对于53°的溢流坝面,坎高超过1.2 m后,水舌冲击压强将大于20×9.8 kPa。Aerator has been provided at the exit of stepped spillway piers,which can avoid cavitation danfer for stepped spillway. Different types of pre-aerators were set on the wide tail pier stepped spillway with physical model at the ratio of 1/25,to analyze the influence of aerator heifht to the effective lenfth,maximum heifht of cavity,air concentration distribution alonf the downstream dam surface and the size of impulsive force. It also made comparative analysis of the conditions without aerator. Experiments show that the size of air concentration alonf the downstream dam surface increases sifnificantly comparinf with that with no aerator;The effective lenfth of cavity increases with the increase of aerator heifht,while maximum heifht has no obvious chanfe when aerator heifht increases;calculation demonstrates that impulsive force increases with the increase of aerator heifht,and it will exceed 20 ×9. 8 kPa for stepped spillway with slope anfel of 53 defrees when aerator is hifher than 1. 2m.

关 键 词：前置掺气坎 阶梯溢流坝 掺气浓度 水舌冲击力 

分 类 号：TV135.21[水利工程—水力学及河流动力学]