Study On Hydrodynamic Characteristics Of High Water-Head Spillway Tunnel With Model Test And Numerical Simulation

Spillway tunnel is one of the common types in the water-power engineering.There is a lot of discharging facilities damage cases because of the improper shapedesign at home and abroad. Therefore, the study of the flood discharge tunnelhydraulic characteristics is of great significance. With the method of model test andnumerical simulation, based on the flood discharge tunnel of a hydropower station inXinjiang province, this paper conducts a study about hydraulic characteristics ofdischarging buildings. In order to achieve the purpose of reducing erosion, it putsforward the method of increasing the aeration facilities and optimizes aerationfacilities body types. From two aspects of hydraulic characteristics and aerationproperties, it demonstrates the rationality of the optimal decision. The main researchesmage by this paper include several aspects as followings:(1)It carried out the flow test under different working conditions by using largescale hydraulic model. Because of small cavitation number in the arch section andanti-arch section, deep hole tunnel will occur the cavitation damage easily, it needs tobe optimized by repairing tunnel size or increasing aeration facilities. Similarly, thesemethods could reduce the bottom cavity backwater after aerator in surface hole tunnel.(2) Based on RNG k-ε turbulence model and VOF method, numerical modelingwas used to simulate the3-D flow fields of dragon-raise section. The numerical modelwas verified by the results of large-scale model test, the computational result andexperiment result agreed well. Two modification proposals of aeration facilities werestudied. The result demonstrates that the aeration facilities can effectively avoid thecavitation damage in the downstream anti-arch section.(3)It checked on the air entrainment model by using the experiment which hasthe measured air concentration, and then analyses the aeration effect about twomodification proposals of aeration facilities in deep hole dragon-raise section, andoptimizing the aerators in small bottom slope surface tunnel by this model.(4) In the research of surface tunnel aerator selection, it puted forward three typesaeration schemes to solve the backwater. Based on model test and numericalcalculation，it determines the optimal solution by the analysis of the bottom cavityform， downstream water-wing， bottom air concentration distribution, verticaldistribution of fracture surface air concentration.