【作者】 夏勇；

【导师】 许唯临；

【作者基本信息】 四川大学 ， 水力学及河流动力学， 2006， 博士

【摘要】 利用导流洞改建为永久泄洪洞不仅可以节省投资,加快施工进度,而且有利于优化枢纽布置,减小峡谷地区工程枢纽的泄洪消能难度。导流洞改建泄洪洞是通过连接段将导流洞段与高位泄洪洞进口相连的,本文主要研究有压流垂直转弯和无压流“龙抬头”两种衔接方式的水力特性。通过大量的常压和减压试验,以及紊流数值模拟,得到如下结果:(1)只要垂直转弯段的转弯半径布置得当,则整个垂直转弯段内不出现负压,加之脉动压力不大,故可保证垂直转弯段具有良好的压力特性。在工作闸门前置的条件下,闸门启闭过程中水流对固壁的冲击力随闸门开度的增加而稳步增加,整个过程中压力过程未出现冲击峰值,竖井的安全运行有充分保证。(2)转弯内径70m、洞径14m的垂直转弯段的初生空化数约为2.61,可供今后此类工程的设计参考。垂直转弯段的空化是完全可以避免的。(3)对于不同的转弯半径,垂直转弯段的流速都表现为内侧大、外侧小,而转弯半径越大,流速在横断面上的分布越均匀,压力系数的变化也越平缓。当转弯半径达到5倍洞径时,压力系数的沿程分布已较好。如因条件限制而难以做到5倍洞径,则转弯半径至少也应大于2倍洞径。(4)试验条件下,“龙抬头”直坡段水流空化数在0.1到0.2之间,直坡段首部掺气坎后声压级差最大值约3dB,考虑到模型与原型之间的空化比尺效应,一般地讲,对于“龙抬头”式泄洪洞,在直坡段首部设置第一道掺气减蚀设施是非常必要的。试验测得的反弧末端固壁附近掺气浓度达2.8%~3.5%,由此表明,只更多还原

【Abstract】 It has many advantages to reconstruct a diversion tunnel to a permanent spillway tunnel: the economization of the investments, the speed-up of the progress schedule, the optimization of the project layout, as well as the reduce of the energe dissipation difficulty in mountain area. The reconstruction key is to built a connection section linking the donwstream diversion tunnel in a lower level with the upstream spillway tunnel in a higher level. The main content in this paper is the research of the hydraulic characteristics in the vertical bend for pressure flow and the dragon head bend for free flow. Based on series of experimental investigations both on normal pressure condition and pressure reducton condition, combining the computation results of mathmatical simulation, the following conclusions can be achieved:First, if the arrangement for vertical bend radius is operable, the negative pressure will not appears in the entire bend and the fluctuating pressure is not big, which will guarantee the the favourable pressure characteristics in the vertical bends.Under the condition of the working gate placed on the entrance of the spillway tunnel, the impact force of flow on solid wall will steadly increase as the gate opening heightens in the operating process of the gate.Because not a sharp value in the pressure process exists, the safe operation of the shaft can be garanteed.Next, the critical cavitation number of the vertical bend with the inner radius更多还原