| In water conservancy and hydropower project,outlet works are a key for the safety of reservoirs.Energy dissipation problem has been always encouraged to research.During the long-term run of Chardara water power station ,it is found that some hydraulic problems are existing: The configuration of bottom outlet bays is the inflection slope in the present configuration of Chardara water power station. Because the configuration of bottom outlet bays is unreasonable and has not been repaired during the long-term run of Chardara water power station. The damage occurs on floor of bottom outlet bays works in various degrees.The flow pattern is poor.The project security has been influent by above problems. By making hydraulic model test , it is found that some hydraulic problems are existing in the present scheme of Chardara water power station:First, the middle piers are separated,so the flow pattern is poor in the outlet ;Second, the configuration of bottom outlet bays is the inflection slope in the present configuration, the configuration of bottom outlet bays is unreasonable.The damage occurs on floor of bottom outlet bays works in various degrees.The flow pattern is poor.Third, configuration of bottom outlet is unreasonable. The flow pattern is poor.As a result of above problems existence, during the long-term run of Chardara water power station, it is found that the flow pattern is poor, the negative pressure exists near the top of the slope in the outlet bay, the cavitation occurs on floor of bottom outlet works. By thinking about the flow pattern, the pressure ,energy dissipation and so on. The configuration of bottom outlet bays resolves those problems which are existing in the present configuration. The result has been accepted by the project.This study used physical model testing.The pilot project is based on the research project, established in the laboratory hydraulic model,which is designed with similarity criterion of gravity. The model scale is Lr=1:40.The model test verification and improve discharge, body building and supporting the layout of the energy dissipation reasonable, research, water discharge and the discharge of energy dissipation effect. To improve the discharge, flow pattern and increase the rate of energy dissipation measures.This research mainly completes following three aspects of work:(1) The modified configuration of the floor of bottom outlet works of Chardara water power station.The configuration of bottom outlet bays is the inflection slope n the present configurationâ… of Chardara water power station. A 1:2.8 slope connects the inlet and stilling basin; Three curve surfaces has been tested. The curve surface floorâ… : Changing the straight line slops into curve surface. The curve equation is y=x~2/84.681; The curve surface floorâ…¡: The slope curve is modified, the equation of which is y=x~2/211.7025. There is a drop at end of curve floor, which is 6m high; The curve surface floorâ…¢: The curve floor is accepted, the equation is y=x~2/423.405, the drop, at end of curve floor, is 8m high. A straight line floor, the drop, at end of straight line floor, is 10m high.The hydraulic model has been tested by making five configurations of bottom outlet bays test. The bringed forward proper configurationâ… of bottom outlet bays ,the equation y = x~2/84.681,is the curve surface floor , is the optimal schemeâ… ,that is the implementation of the scheme.Experiments show that this type of weir parabolic surface can remove the top running condition weir near the negative pressure, improve the properties of space and avoid the weir near the top of the cavitation damage.(2) In order to solve the problem that is the oversized height of baffle blocks in the present scheme, the hydraulic model has been tested by making eight layout forms of baffle blocks test.. Layout 1 of baffle blocks in the present scheme but the hight should be reduced to 4 m; Layout 2 of baffle blocks in the present scheme but the hight should be reduced to 3 m; Layout 3 of baffle blocks in the present scheme Takes upstream one baffle blocks to disappear, downstream two stilling the same baffle blocks ,but the hight should be reduced to 5 m; Layout 4 of baffle blocks, Take the upstream baffle blocks to move to the downstream to the line of position of the downstream baffle blocks, the hight is 4m; Layout 5 of baffle blocks, take the upstream baffle blocks to move to the downstream to the line of position of the downstream baffle blocks, the The both sides baffle blocks hight is 4m; Layout 6 of baffle blocks in the present scheme but the hight should be reduced to 3 m, downstream into three baffle blocks and uniform, and on both sides of stilling baffle blocks hight reduced to 4m; Layout 7of baffle blocks,Take away of the upstream baffle blocks, the three downstream baffle blocks and uniform, hight reduced to 3m; Layout 8of baffle blocks, Takes away the upstream and downstream of baffle blocks, in the downstream baffle blocks under baffle blocks terminal to move to 2m to arrange 4 baffle blocks and uniform, hight reduced to 4m. The hydraulic model has been tested by making eight layout forms of baffle blocks test and 96 rows of observed combination test.The results show that the existing baffle blocks layout forms that is reasonable and feasible: Optimization ofâ… middle pier + layout forms of baffle blocks in the present scheme but the hight should be reduced to 4 m, the condition of water jump conveniently located, better flow pattern to meet the engineering requirements.(3) On the basis of optimized scheme test of 5 the configurations of bottom outlet bays and 8 layout forms of baffle blocks,after making different combination of optimization tests.Get the final implementation scheme are: Optimizationâ… middle pier + layout forms of baffle blocks in the present scheme but the hight Should be reduced to 4 m. The scheme successful resolution the problem of the inflection slope stilling basin existing in the present scheme slope problems, the result has been used by the project.This test solved hydraulics problem in middle outlet of Chardara water power station.the result has been used by the project.
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