泄洪洞变底坡掺气坎掺气特性研究

Study on aeration characteristics of variable bottom slope aerator of spillway tunnel

针对高水头小底坡泄洪洞采用常规挑(跌)坎存在的空腔回水现象严重、稳定性差、水头变幅适应性差等问题,通过模型试验的方法,结合如美水电站放空洞,对“挑坎+平缓坡+陡坡”的变底坡形式掺气坎进行系统研究,揭示了变底坡掺气坎各部位(挑(跌)坎、平缓坡段以及陡坡段)对掺气空腔的影响机理。结果表明:在水位大幅变化过程中,变底坡掺气坎对应的空腔充满回水的临界水头值为73.5 m,比常规掺气坎提高了29.4 m。研究结果可为高水头小底坡泄洪洞的掺气设施布置提供参考。

In response to the serious problems of high head small bottom slope spillway tunnels with conventional flip bucket(drop bucket),such as cavity backflow,poor stability,and low adaptability to head variation,the variable bottom slope form of aerated bucket with"flip bucket plus flat gentle slope plus steep slope"was systematically studied through model test combined with the emptying cavity of Rumei Hydropower Station,and the influence of various parts of the variable bottom slope aerator(flip bucket,gentle slope section,and steep slope section)on the aerated cavity were revealed.The results showed that during the significant change in water level,the critical head of the cavity filled with back water corresponding to the bottom slope aerator was 73.5 m,which was 29.4 m higher than that of the conventional aerator.The research results can provide a reference for the layout of aerated facilities in high head small bottom slope spillway tunnels.