Research On Hydraulic Characteristics Of Reconstructing Diversion Tunnel To Permanent Spillway Tunnel

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...