Three-dimensional Numerical Simulation Of Aerated Flow Downstream Of Aeration Slot In Spillway

With the rapid development of high dam construction in china, a large number ofhigh dams and hydropower stations are being, or is about to be constructed. Thesehigh dam water-release structures generally have the characteristics of high head,large discharge and narrow valley. The discharge gets bigger and bigger and unitwidth discharge increases further. The flow rate is up to40m/s and some even exceed50m/s. The cavitation number of water flow is smaller, resulting in some of thewater-release structures over the flow areas often occur severe cavitation damage. Thedomestic and foreign projects indicate that aeration is an important measure to preventwater-release structures from cavitation erosion. Therefore, study on hydrauliccharacteristics of aerated flow of spillway will be of great importance in safeoperation of water-release structures.This paper adopts k-ε mixture turbulence model to solve the Reynolds Stressequation and two-fluid model and Eulerian method to process the free surface and itsinteraction. Three-dimensional numerical simulation is made research on the aeratedflow downstream of aerator. Compared with the VOF method, two-fluid model andEulerian method has some advantages for studying aerated flow. The turbulencediffusion is taken into account in establishing the constitutive equation of drag force,also the transfer characteristics of water-air interface are considered. Therefore, theflow characteristics of water-air dilution and separation can be simulated better.The test conditions are calculated using the three-mathematical model of aerationslot. The water flow pattern; water surface line; bottom pressure distribution; velocitydistribution; air entrainment concentration distribution, and unit width quantity ofentrained air, et al are achieved. Numerical simulation results have been betterverified with the experimental data, which proves the feasibility that two-fluid modeland Eulerian method is used to study the aerated flow of the spillway.Aerated flow downstream of aeration slot in spillway is studied in detail applyingthe validated mathematical model above, discussing the relationship between theaerator height, slope, velocity and quantity of unit width entrained air. The researchachievements offer some valuable references to similar project design.