高坝工程坝身孔口射流多呈横向扩散下泄,但狭窄河谷中的高坝工程因泄流宽度不足而受到限制。在坝身孔口出流末端设置横向收缩折流板,可获得竖向及纵向扩散良好的窄长水舌流态,从而充分利用河道纵向空间泄洪消能。但折流板两侧因射流冲击而压力剧增,这对折流板的结构设计不利。通过模型试验的方法,对收缩射流折流板不同体型参数(收缩比β、相对收缩段长度δ以及出口倾角γ)和深孔进口水头变化对其所受冲击压力的影响进行了研究。结果表明:射流冲击使得折流板上所受压力剧增,且压力最大值出现在始折点(突扩侧墙与折流板相接处,即折流板的始端)上,折流板面上无负压出现;折流板最大冲击压力随收缩比的增大而减小,随相对收缩段长度的增加而减小,随出口倾角的增大而增大,随深孔进口的水头增加而增大。
Abstract
Flow from the orifice of high dam usually fall with full diffusion in horizontal direction, but in narrow valley it is limited by the width of river. By setting transverse shrinkage baffle plates at the end of the dam orifice, the flow jet becomes narrow and long spreading well in vertical and longitudinal directions, which gives full play to the longitudinal space of river for flood discharge and energy dissipation. However in this case, the pressure on the baffle plate surged due to jet impact, which is detrimental to the structure design of the baffle plate. In this paper, the impact pressure on the baffle plate was researched by changing the shape parameters of baffle plate (contraction ratio β, relative contract length δ and outlet angle γ) as well as water head at the entrance of orifice. Research results revealed that the maximum pressure on the baffle plate was at the beginning point (which is at the joint between suddenly-enlarged side-wall and baffle plate), while no negative pressure was found on the baffle plate which is beneficial to alleviating cavitation of the plate. The maximum impact pressure reduced with the increase of contraction ratio and relative contract length, while increased with the increase of outlet angle and water head at the entrance of orifice.
关键词
高坝工程 /
高速射流 /
泄洪消能 /
折流板 /
压力特性
Key words
high dam project /
high-velocity jet flow /
flood discharge and energy dissipation /
baffle plate /
pressure characteristic
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基金
国家自然科学基金青年科学基金项目(50909067,51009102,51179113);新世纪优秀人才支持计划(2011SCU-NCET-10-0589)
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