泄洪洞反弧段上游掺气坎对反弧段下游侧墙的减蚀作用

通过对龙抬头明流泄洪洞反弧末端下游易蚀原因的总结分析,指出在设计掺气坎时应重视反弧段下游附近边墙的掺气防护。通过大比尺模型试验,对能否通过增加反弧段上游掺气坎的掺气能力达到对反弧段下游侧墙的减蚀目的的问题进行了研究,试验表明:增加反弧段前掺气坎的掺气能力,虽然能在一定程度上改善反弧段下游边墙的掺气效果,并减小边墙清水区范围,但反弧段前掺气坎的掺气能力即使较大时,也难以完全消除边墙清水区,该措施难以可靠地解决反弧段下游边墙的空蚀问题。

Effect of upstream aerator in ogee section of spillway tunnel on cavitation alleviation of downstream sidewall

Based on an analysis of causes of cavitation damages to the downstream at the end of ogee section in the spillway tunnel of open channel,it is pointed out that the aeration measure for sidewall protection nearby the downstream of ogee section should be paid much attention in aerator design.Large-scale model tests were performed to study whether the cavitation alleviation of downstream sidewall in ogee section can be realized by enhancement of the aeration capacity of upstream aerator.The results show that the enhancement of the aeration capacity of upstream aerator can improve the effect of aeration on downstream sidewall to a certain degree and reduce the clean water region of the sidewall;but it cannot eliminate the clean water region completely.Therefore,it is difficult to control cavitation of downstream sidewall thoroughly only by this measure.