Study On Hydraulic Characteristics At Intakes Of Hydropower Stations

Because of lacking enough understanding and research on the relation betweendams and ecology, intakes of hydropower station mainly adopt conventional design,which withdraw the deep layers of water. For the present, the achievements onhydraulic characteristics of conventional pressure intakes are very abundant. But theachievements mainly are directed at a certain project, which have limitations andpractical relevance and lack systematical and regular summary for similarengineering.With the development of the construction of the water conservancy and waterelectricity, intakes of conventional design can no longer meet the requirements fordownstream environmental protection. As a new type of withdrawal in the practicalengineering, Multi-level intake structure can withdraw selectively different layers ofwater. Multi-level intake structure can efficiently control the temperature and qualityof reservoir water released and can reduce the effect of releasing cold water ondownstream living being and water environment. Therefore, multi-level intakestructure is adopted more and more in engineering design. However, the flowcondition of intakes will become very complicated and the characteristics of flow willchange enormously. The current related study on multi-level intake structure at homeand abroad is far away from mature.This paper systematically investigates hydraulic characteristics at conventionalpressure intake, double-level intake; multi-level intake of hydropower station bynumerical simulation method.(1) The study on hydraulic characteristics at conventional pressure intake.Conventional design are adopted in the intakes of Ertan hydropower station，Xiaowanhydropower station, Hongjiadu hydropower station and Tianshengqiao hydropowerstation I. Combined with above engineerings, a3D numerical simulation is made onthe hydraulic characteristics at intakes with k-ε turbulent model; from which the headloss, velocity distribution, flow pattern, etc. are summarized. The flow fieldcharacteristics at intakes of different bodily form are analyzed. The water movementlaws at conventional pressure intakes are summarized.(2) The study on hydraulic characteristics at double-level intake. Based ondouble-level intake of Nuozhadu hydropower station, the head loss and the velocitydistribution of different level intake are researched. The changes of flow field ofintake are discussed. And the impacts of different position of withdraw water on velocity distribution of the flow in reservoir are analyzed.(3) The study on hydraulic characteristics at multi-level intake. Based onmulti-level intake with stoplog gate of Nuozhadu hydropower station, the head lossand the velocity distribution at different height of stoplog gate are researched. Thecharacteristics of flow field from the top of stoplog gate into vertical flow channel arediscussed. The impacts of the water level, the width of intake chamber, the number ofoperating sets on hydraulic characteristics of the intake are analyzed.(4) Hydraulic characteristics of intakes of hydropower stations are systematicallyresearched by numerical simulation method, the water movement laws are fullyrevealed. A comparison of the calculations with the measurements gives a fairly goodagreement. This shows the effectiveness of the methods adopted and the researchmethod can be applied to the related practical projects.