挑流式底栏栅取水的初步研究

A PRELIMINARY STUDY ON BOTTOM GRATING INTAKE OF SKI JUMP TYPE

底栏栅取水工程设计及运用存在的主要问题是廊道从河流层取水,引进沙量较多,易造成底栏栅堵塞及渠道淤积,磨损水轮机等。本文根据山溪性河流的特点,提出利用挑流式底栏栅取水,其功用为:①利用挑流排泄漂浮物,减少水中漂浮物堵塞栅隙;②由于取水廊道顶上底栏栅坡度小于零,相应增加了廊道进水流量系数,可减小栅条间距;③利用推移质卵石对底栏的碰撞,可减少和排除堵塞底栏栅的漂浮物和卡石,从而达到引水防漂防沙的目的。

Bottom grating intake of the conventional type has the drawback that river bed load may block up the bar screen and cause sedimentation in diversion canal. Based on the analysis of the characteristics of moutain stream, we propoes in this paper the bottom grating intake of ski jump type. This practice offers at least three functional advantages over the conventional one by 1) preventing the drift from blocking the screen, 2) increasing discharge coefficient, because of i<0 where i is bottom screen slope, to permit reduced screen gaps, 3) making use of collision of bed load with bottom screen to attenuate silting up.