有压出流条件下突扩突跌掺气设施空腔长度研究

掺气减蚀措施可以减免高速泄水建筑物的空蚀破坏。采用突扩突跌掺气设施,会同时形成底空腔及侧空腔,获得较好的掺气减蚀效果,对建筑物底板及侧墙均起到良好的保护作用,在有压出流条件下,通过对突扩突跌掺气设施水工模型进行不同突扩宽度、跌坎高度、下游坡度、来流条件下的模型试验,初步确定了跌坎高度、突扩宽度、下游坡度对空腔长度的作用方式。结果表明,有压出流条件下,在其他条件相同时,底空腔长度与突扩宽度、跌坎高度均呈正相关关系,与下游坡度呈反相关关系;侧空腔长度与突扩宽度呈正相关关系,与跌坎高度及下游坡度均成反相关关系。最后通过量纲分析拟合出有压出流条件下,相对侧空腔长度与综合水力参数X的关系,得到在X<8时计算侧空腔长度的经验公式。

Study on the Cavity Length of Sudden Lateral Enlargement and Bottom Drop Aerator Device Under the Condition of Pressure Flow

Air entrainment and cavitation alleviation can relieve the cavitation damage of the high-speed discharge structure. Use of the sudden lateral enlargement and bottom drop aerator device can form both bottom cavity and lateral cavity, which can protect the bottom plate and side wall and therefore play an important role in the air entrainment and cavitation alleviation. Hydraulic model tests were performed on a sudden lateral enlargement and bottom drop aerator with different sudden expansion widths, down ridge heights, downstream slopes, and flow conditions under the condition of pressure flow. The impacts of sudden expansion width, down ridge height, and downstream slope on cavity length were initially identified. The results indicated that under the condition of pressure flow, the bottom cavity length has a positive correlation with the sudden expansion width and down ridge height but a negative correlation with the downstream slope; while the lateral cavity length has a positive correlation with the sudden expansion width but a negative correlation with the down ridge height and downstream slope. Finally, the relationship between the relative lateral cavity length and comprehensive hydraulic parameter X was determined under the condition of pressure flow, and an empirical equation to calculate the lateral cavity length was derived when