峡口拱坝消能方式的选择和计算

Selection and calculation of energy dissipation scheme for Xiakou arch dam

通过试验研究,将峡口表孔布置为大差动高低坎泄水方式,两侧边表孔采取高挑坎,中表孔采取低挑坎.在拱坝的向心作用下,边表孔的水舌与中表孔的水舌在空中相互交汇碰撞,可提高整体消能效果,明显减轻坝下冲刷.理论分析表明,上下水舌的交汇角越大,碰撞率消能率越高.改变中、边表孔的挑坎高程差和各自的挑角,可增大上下挑射水舌碰撞角度,提高空中消能率.峡口水电站的交汇角为37°,计算空中消能率为9%.

By model test, three surface spillway sections of the Xiakou Hydropower Project are laid with differential elevations of deflector buckets. Two surface spillway sections on two sides adopt high elevation bucket while the middle and surface one in arch center has low elevation bucket, forming large differential outflow. The jet flows from different buckets collide with each other and dissipate energy in the air. As a result, the depth of the downstream pit can be reduced. Changing differences and angles of buckets can change the angle of the jets. The larger the angle of the jets , the more efficient the energy dissipation. The angle of the jets in the Xiakou Hydropower Project is 37°, and efficiency of energy dissipation in the air is 9%.