泄洪洞突扩突跌掺气设施水力特性研究

Research on Hydraulic Characteristics of Spillway Tunnel with Sudden Lateral Enlargement and Vertical Drop

有压洞出口突扩突跌掺气设施在工程中得到广泛应用,合理的突扩突跌体型能较好的对水流掺气,进而减小水流对泄水建筑物的空蚀破坏。利用Eulerian的RNGk-ε三维紊流数学模型及物理模型试验对突扩突跌掺气设施的水力特性进行了研究,得出突扩突跌后底空腔及侧空腔的变化规律及影响因素。水流掺气浓度在水舌落点附近最大,其分布受贯通的底空腔尺度和侧空腔尺度的综合影响。侧掺气空腔对增大泄槽边墙附近的掺气浓度效果显著,对水舌落点以后的明槽段,同一流程位置边墙附近的掺气浓度比中轴线处平均可增大10%-30%。研究结果有助于了解突扩突跌掺气设施的水力特性,可为选取该设施合适的体型尺寸提供参考。

The sudden lateral enlargement and vertical drop aeration facilities at the end of pressure tunnel has been widely applied in the engineering practices .In order to have good water aeration to protect water release structures from cavitation erosion ,the rea‐sonable type and size of this facility is needed .Based on the Eulerian Method with RNG k-ε3-D turbulent model and model experi‐ments ,the hydraulic characteristics of flow from this aeration facility have been investigated .The bottom cavity length and lateral cavity length after this aeration facility by numerical simulation and model experiments have been obtained and the factors affecting to both the bottom and lateral cavities are discussed .The air concentration in the flow downstream the sudden lateral enlargement and vertical drop aeration facility reaches its maximum value in the region near the water tongue placement .The air concentration distri‐bution in the water flow is determined by connected bottom and lateral cavities .The role of lateral cavity to improve the air concen‐tration in the flow region near the side walls is remarkable .Downstream the water tongue placement in the same flow cross section , the air concentration in the flow near the side walls is about 10% -30% bigger than that at the middle of cross section .The results of the study are helpful to realizing the sudden lateral enlargement and vertical drop＆#39;s hydraulic characteristics and can provide a refer‐ence for selecting aeration facilities .