| With the establishment of west development stratagem, most conservancy projects have many characteristics in common, such as the high head, the large flow and the large flood power. The problem of the dam's energy dissipation is more obviously. How to make sure the flood with huge energy discharging safely, out of the question, is the key technique during the construction of the high dam.Energy dissipation by hydraulic jump is a traditional way to dissipate energy. The energy can be dissipated through the surface swirl and the violent turbulent motion that caused by the hydraulic jump. The characteristics of this kind of energy dissipation are :high percentage of energy dissipation,tiny tail fluctuation, low foggy affection of flood-relief. How to increase the percentage of the energy dissipation is the aim of the study to technique of energy dissipation by hydraulic jump for a long time. In the 1970s, much study was done to increase the percentage of the energy dissipation with low head water but large discharge. Wide end pier is adopted to change the flow pattern of intake water flow in baffle basin in order to form three dimensional flow to increase the percentage of energy dissipation during the "85" Technique Break. Recent years, with the improvement of realization to soil and water conservation and environment protection and the improvement of requirement, because of the downstream desilting and the serious fogy phenomenon and water falling caused by energy dissipation by ski jump type which greatly destroy the soil and water conservation and environment to the downstream region. So, energy dissipation by hydraulic jump not the ski jump type is adopted in many engineering that are being constructed or will be constructed. Under the flood discharge condition of high head water and large discharge, the energy dissipation by hydraulic jump is adopted. As for it, problems from two aspects should be solved: on the one hand, howto not only improve the percentage of energy dissipation but also make sure the flow with huge energy safely is discharged; on the other hand, how to make sure the safe and stabilization of energy dissipater itself, because the energy dissipater is easily destroyed by many high hydraulic guidelines such as the high flow velocity near to the floor and the pulsating pressure.The lip energy dissipater basing on the energy dissipation by hydraulic jump is a new energy dissipater suiting to high head water and large discharge. It not only improves the percentage of energy dissipation, but also eliminates the affection of fogy. Compared with normal energy dissipater by hydraulic jump, the hydraulic guidelines in the baffle basin are greatly decreased. Now the study to the lip energy dissipater basing on the energy dissipation by hydraulic jump is being done and used in practical engineering, for example, the Xiang jia ba hydropower station and the Jin an qiao hydropower station. However, because of the absence of systematic basic researches and results, it is almost blank in the aspect of the study to hydraulic characteristics, especially the characteristic velocity, the distribution of eddy scale strength , the distribution of turbulent energy in the baffle basin and the percentage of turbulent dissipation.The thesis bases on the Natural Science Fund Item (2006E0018M) 《the study of lip energy dissipater's hydraulic characteristic basing on the energy dissipation by hydraulic jump》 . The energy dissipation mechanism to lip energy dissipater by hydraulic jump and the mechanism to decrease the high flow velocity near to the floor are analyzed theoretically, the main effective parameters of lip energy dissipater hydraulic characteristics are also studied, and then some theory results are educed. The hydraulic characteristics in the baffle basin are observed through changing the intake energy,the intake unit flow, the intake angle and the depth of the lip. Comparing the theory study results and the test results, correlative theory is verified inthe thesis. |
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