Numerical Simulation Study On Characteristics Of Aeration Flow In Spillway Tunnel

How to protect release works with high-speed flow against cavitation erosion is one of the key problems in the high dam constructions. Cavitation control by aeration is proved by a great of projects to be an important, a useful and an economical technique for preventing cavitation damage. Behavior, mechanism and application of air entrainment for cavitation damage control have been investigated for more than60years. However, severe cavitation damage happened due to complex mechanism of air enterainment. Under some special hydraulic and geometry boundary conditions, cavitation erosions maybe occurred both on the sidewalls and on the bottom of release works. So the aeration facilities both on the sidewalls and on the bottoms of the discharge works should be explored to protect the concrete surface of the discharge works from cavitation damage. But until now, systematic and deep research work on these problems is not reliable.In order to protect the all cross section of the water release structure against cavitation erosion, combining with sidewall and bottom plate aeration for preventing cavitation erosion measures must be taken. In this paper, study the aeration flow characteristics, characteristics of the aerated cavity, hydrodynamic pressure along the flow direction, aeration concentration regulation along the flow direction and effective aerated protection length with sudden lateral enlargement and bottom drop at the flood discharge tunnel pressure outlet by the method of numerical simulation of three-dimensional turbulent flow model.Based on summarizing the predecessors’ research results, Eulerian Method with RNG k-ε turbulent model was adopted to carry out three-dimensional numerical simulation on the aeration facilities both on the sidewalls and on the bottom of release works. Conduct the comparative analysis between the experimental results and numerical simulation to verify the correctness of the numerical simulation methods. The main achievements of this paper are followed:the flow pattern after different aeration, the influence factors of the cavity characteristics, hydrodynamic pressure distribution rule in the impact area of flow, the distribution law and attenuation law of aeration concentration, effective areated protection length, etc. The research work provides more reliable theoretical basis for cavitation control by aeration facilities on water release structure of high dam constructions.