Investigation For Aeration Devices In High Water Head Sluice Tunnel

With the development of the dam construction technique, high head, huge height of waterand large flood discharge power,etc.from the high dam built on alpine and gorge region,whichcould cause the cavitation erosion problem increasingly prominent. Compared with shapeoptimization,reduce roughness of flow surface and the use of cavitation erosion resistancematerials, arrangement of aerator is a kind of more effective measures to alleviate cavitationerosion. On the basis of extensive investigation, according to1:30monomeric hydraulic modelof free-flow tunnel of No.3sluice tunnel of Wudongde Hydropower Station, adopting thecombination of model experiment and numerical simulation, studied the hydraulic characteristicsof the aerator, the following results were obtained:(1) Through the experiment, the fluid state, free water surface, characteristics of pressureand cavity characteristics of aeration in the free-flow aera of the tunnel without aerator wereobserved. The layout of the position and size of aerator shape of three kinds of aerator plan weredesigned which based on the previous experiment, and carried on the experimental study onaerator which could alleviate cavitation erosion.(2) The experiment results show that sectionflowaverage velocity of the curve connectionsection of free-flow aera ofthe tunneland the following aera could be more than30m/sbottom.pressure along the bottom changed gently, but curveconnection section of bottompressure is low, the flow cavitation number may be less than0.3, aerator should be taken toalleviate cavitation erosion. According to the experiment data, the position and size of aeratorshape of three kinds of aerator plan were designed, and the corresponding corrosioninhibitoreffect validation of experimental study were conducted.Comprehensive comparison ofthree kinds of schemes of aeration effect, it is recommended to use scheme III aerator at thebottom of the tunnel for the water aeration.(3) The hexahedral structured grid of uneven density were applied on the whole calculationarea which derived from3D modelof free-flow aera ofthe tunnelbased on model experiment,andthe boundary conditions of numerical simulation were calibrated by model experiment datas.(4) The standard κ-ε turbulence model and VOF model and Eulerian model were applied tocarry out the three dimensions numerical simulation of the aerator in sluice tunnel.Free watersurface,hydraulic characteristics on the aerator,cavity characteristics of aeration,air concentrationdistribution along the centerline of the bottom of the channel behind the aerator have been obtained.The result of the numerical simulation shows that the VOF model and Eulerian modelcan be used to simulate hydraulic characteristics of the aerator and cavity shape of aeration to acertian extent.Overall, compared with VOF model, the Eulerian model has a better simulationprecision to a certain extent, in terms of the numerical simulation carried on the aerator of thesluice tunnel.(5)The use of numerical simulation could improve efficiency of hydraulic engineeringdesignand saving cost, and providing earlier forecasts and guidance for model experiment and itsresults as a basis forcomplement of model experiment. the numerical simulation methods andresearch results presented in this paper is available for similar engineering as a researchreference.