The Study Of Flow Characteristics And Energy Dissipation Inside Non-pressure Tunnel Under Variable Water Head

In our countruy, it exist the common phenomenon of uneven distribution of water resources. Not only do the north and south area have the serious differences of water resources, but also that exist in the same area. And in recent years, coupled with the ecological environment has been seriously damaged, water pollution is serious, water shortage problem has increasingly become the focus of attention. Therefore, the constructions of water conservancy facilities become an important way to adjusted distribution of water resources to solve the shortage of water resources.The diversion tunnel is the main building of water conveyance structures, and it concludes non-pressure release tunnel and pressure diversion tunnel. Diversion tunnel is often encountered in operation pattern which are disorder, excessive of current velocity, cavitations, alternative and other hydraulic problems. So the flow characteristics inside the tunnel and energy dissipation are both needed to consider in the design of water diversion tunnel, which is critical for the normal operation of the diversion tunnel even the entire engineering safety.This paper takes water supplied project as the research object. It mainly studies water flow characteristics and energy dissipation of non-pressure release tunnel under the condition of variable head by physical model test. The non-pressure release tunnel in this project has the following characteristics, high water head, large amplitude, high velocity, the complex gate operation, difficult arrangement of the energy dissipater. In the model test, we study the flow characteristics of non-pressure tunnel by operating the gate, and measuring the velocity, water surface curve, the pressure and other hydraulic factors under the of variable head.Meanwhile, as for energy dissipation of non-pressure tunnel, we break the conventional hole outlet energy dissipation, and lay out the internal dissipater to dissipate the energy. In the test process, stilling basin is taken into the internal tunnel to study the dissipation of energy. Through the optimized design of stilling basin, the flow pattern inside the tunnel has improved which can reach a certain dissipation effect and satisfy the project requirement.This paper minly studies the flow characteristics and the internal dissipater of the non-pressure release tunnel under the variable head on the basis of model test. The consequence can be provided with design basis for this project as well as for the similar project.