泄洪洞侧墙的人工强迫掺气减蚀研究

采用常见的底部掺气设施时,反弧段下游附近边墙仍存在较大范围的掺气盲区,从而反弧段下游边墙容易产生空蚀破坏。利用反弧段上游掺气坎空腔进行人工强迫通气的试验表明,增加反弧段前掺气坎的掺气能力,虽能一定程度减小反弧段下游边墙的清水区范围,但难以将其完全消除。反弧段下游边墙清水区直接强迫通气的试验表明,通过边墙通气孔进入水流的气体扩散范围很小,且由于沿边墙高度各点动水压力不一样,很难保障沿边墙高度掺气的均匀性;同时,强迫通气所需的动力设备功率很大。因此,在实际工程中采用人工强迫通气减免反弧段下游侧墙的空蚀难度很大。

Study on Artificial Aeration in Cavitation-Protection for the Sidewalls of Spillway Tunnel

When the common bottom aeration facilities is used, the downstream sidewalls near the anti-arch section still has big-range un-airflow area so that it is easy to cause cavitation damage. Based on a large-scale model experiment, it is not easy to eliminate the un-airflow area in the sidewalls at the backward of anti-arch section for artificial aeration. In the experiment aerating from the air chamber formed by the arrator at the upward of anti-arc, the un-airflow area in the sidewalls at the backward of anti-arch section can be weakened to some extend under the larger airflow rate of the anti-arch upward aerators, yet it can not be eliminated completely. In another experiment aerating from the un-airflow area in the sidewalls, the diffused area of airflow aerating from sidewalls is small, and water pressure along vertical sidewalls is varied, the airflow can not be aerated equably. Furthermore, the power needed by artificial aeration is quite enormous. Therefore, it is very difficult in practice to adopt artificial aeration to alleviate the cavitaiton damage in the downstream sidewalls near anti-arch section.