Study On Air Entrainment To Alleviate Cavitations For Downstream Sidewalls Of Ogee Section In Spillway Tunnel

Ogee spillway tunnels are widely used in middle or high head water conservancy and hydropower projects. Its main problem in projects is cavitation damage of ogee section, which can be frequently found in the end, downstream baseboard and downstream sidewalls of ogee section. The aerators are normally designed to inhale air from the bottom to slove this problem. According to operation of projects, the cavitation damage still exists at downstream sidewalls of the ogee section despite using this normal aerators. What we need to study are: why do the cavitation damage still exist and what kind of measure can alleviate it effectively. Since the downstream flow of ogee section in large spillway tunnel is normally characterized by high speed, large discharge, low Fr and slight slope of the channel, it is difficult to design the shape of aerators to alleviate cavitations. The influence of centrifugal force on the flow at the end of ogee section makes the design work more difficult. It is significant to study how to optimize the shape of aerators for this kind of spillway tunnel.Based on large-scale model experiments and numerical simulation of turbulent flow, the reasons of caviation damage, which still exist after using normal aerators, were analyzed in this paper. The air entrainment plans of solving cavitation damage for downstream sidewalls of ogee section were also discussed. In addition, some suggestions optimizing the shape of areators in slight slope of the channel and low Fr...