Experimental Research On Energy Dissipator Of Diversion Works In Low Head

In low water head diversion works, a common hydraulic problem is energy dissipation about low Fr. number hydraulic jump, which energy dissipation is less efficiency and there are large waves in downstream, and the shores is cut, and influenced the operating of hydraulic energineering, and worsened the the erosion of the river bed . The question that how to solve the problem of the energy dissipation and erosion control effectively in the condition of the low head and low Fr. hydraulic jump and high single breadth discharge is a common diffcult problem of diversion works in low head.In this paper, the energy dissipation and erosion in the low Fr. hydraulic jump is object of studying. The hydraulic model in lab is made according to the basal data that is offered by design unit. By the hydraulic model, the original design scheme is verified, and a feasible measure of the flow regime, and flow velocity, and topography of scouring and silting, the wave and damping ratio. Then the energy dissipaters are selected according of the theory the conditions . At last, a kind of reasonable energy dissipater is proved to resolving the problem of the energy dissipation and erosion in diversion works in low head.In this article, a new type energy dissipater, T-shape pier is lied on cement-rubble apron, which is used in energy dissipation and erosion of low head and low Fr. hydraulic jump and high single breadth discharge, is bring up. In order to verify the effect of the energy dissipation of T-shape pier , author of this article has done some experiments and made some summaries from those experiments. The base of this summary mainly relies on the following points: the flow states of the current, the velocity distribute of the current, the erosion extent of the river bed and the condition of the current wave and damping ratio etc. In the same time, we compare the effect of energy dissipation of this new T -shape pier with other energy dissipater.Through the research we find that the velocity of the bottom current and the fluctuation velocity and the energy of the turbulence are the most important factors affecting the erosion of the river bed. Because of the T -shape pier, the flow was hamper to high , and which changes the flow direction , and which enlargement the upper stream water current roll, especially the flow in downstream of the T-shape pier became bigger and many stalks to roll, and which enlarges the water roll and mixing , which promotes theconversion and dissipation, enlarges the water current of the water current energy the energy dissipation, and break originally possessed the water current's big dimensions whirl, changes the big dimension whirl to the small dimension whirl, reduces the turbulence energy of the downstream.By the analysis, we conclude that T-shape pier attains a better energy dissipation effect. When the current of low Fr. passes through this energy dissipater, the velocity of the bottom current, the turbulence, the wave and the erosion control are less than the other energy dissipater. There are also some advantages as following besides some mentioned above: the structure of the construction T-shape pie is sample, the construction is convenient , engineering quantity is saved, which can used in proposed and completed hydraulic engineering. In the same time, T-shape pier don't applied some supplementary structures in stilling pool which scours the stilling pool in large flood discharging and rub the energy dissipaters and slit up the sand and brings local roll. In brief of T- shape pier energy dissipater reserves the abroad practice.