Study On Energy Dissipation Characteristics Of Multiple Jets And Its Applying For Pressed Water Pipeline Outlet

The submerged porous sleeve valve is served as a new type of energy dissipater for pressure pipeline outlet, by which fluid energy of pipe outlet can be dissipated through entrainment and mixing of the high speed flow shot out from the multiple jets at multilevel into the plunge pool, in which strong turbulent flow can be produced. Energy dissipation ratio depends on the sizes, quantity and layout of the nozzles. At present, the researches on pipeline with multiple jets mainly concentrate on the blending problem in power engineering and the physical diffusion problem in environmental engineering. Whereas few researches on using turbulence of multiple jets to dissipate the dump energy of pipeline outlet are made. According to the engineering application, it is urgent to study its flow distribution and dissipation characteristics. Its study results will provide scientific basis for the design of the valve chamber. It will have very important significance for engineering application.In this paper, combining the Project of Diverting Water of Yellow River Shanxi Province, the complicated flow of energy dissipation multiple jets for pressure water pipeline is studied by numerical simulation and testing on the basis of previous researches. The main contents and achievements were as followed:(1) Based on experimental study and numerical simulation, it has firstly been systematically studied for the complicated flow of energy dissipation of multiple jets for pressure water pipeline export. It has firstly simulated the complicated flow of energy dissipation of multiple jets for pressure water pipeline export. The results being referenced for designing and further research have been obtained. Adopting RNG k-εturbulence model, it has realized the three-dimensional numerical simulation of the new scheme of energy dissipation, studied the optimum arranged way of hole, compared the now and then equal flow distribution characteristic when the number of gushing hole changed, and discussed energy dissipation mechanism of this dissipater as well as other waterpower characteristic property.(2) The concept of section remained energy ratio is presented, by which the dissipation energy effect at different hole number and arranged way of hole are analyzed. The results indicated that: dispersing degree of jet momentum almost decided energy dissipation effect, and efficiency of dissipation energy dissipater was decided by the size, quantity, and arranged way of the hole. The dissipation energy effect of plum blossom shape arrangement is obviously better than parallel one. The curve of section remain energy ratio concept was given when the hole number changed. When the number of holes increased, the effect of energy dissipation can effectively rise, but the number increased to certain one, the change notably slow down. As a result, it is no need to illimitably increase the number of holes.(3) It has analyzed and discussed the flow structure and energy dissipated mechanism when multiple jets come into the valve room. Study showed that: when multiple jets come into the water, the contact area between jet current and the vicinity wave increased evidently, and rapid attenuation of energy was found at the region from outlet 0.41 m. In addition, entrainment and mixing of the high speed flow shot out from the multiple jets at multilevel into the plunge pool formed strong shearing eliminating energy area, so the efficiency was comparatively high. At the same time, since every eddy interacted, it may have an effect to diminish the scour of the wall of valve room.(4) Energy dissipation of multiple jets for pressure water pipeline export was successful applied on the Project of Diverting Water of Yellow River to Shanxi Province and it has already obtained remarkable economy and technology benefits, which has laid down solid basis for the application of energy dissipation of multiple jets for pressure water pipeline export. The impact of shape and size of flow characteristic property of valve room has been studied by the three-dimensional numerical simulation. The optimal shape of valve room of energy dissipation has been chosen out, which has the best effect of Energy dissipation. The models of optimization valve room, plunge pool behind the weir and water-entering front pool were tested. Flow structure has been observed on various working condition, and many waterpower parameters have been obtained such as the velocity distributing, water surface, and energy dissipated rate. Test indicated: The regulating valve room has some advantages of small field area and high eliminating energy efficiency, and ensures that stream enters lower reaches stably, and has effectively resolved the energy eliminating problem of the pressure pipeline exports.(5) Model experiment has been carried out and the design plan has been perfected for energy dissipation problem of pressure water pipeline export under no control of discharging. The size of the hole on the erect pipeline of energy dissipation, arranged way and general area of hole have decided by experiment and it has also resolved energy dissipation problem of pressure water pipeline under the condition of large closure water-head and widely discharge variation. It has ensured the operation condition of water conveyance of pressure pipeline and make water flow enter lower reaches stably. It has also provided precious experience for flow adjustment and the energy dissipation at the outlet of pressure pipeline.