ABSTRACT
High-speed flows will bring many special hydraulic problems, such as strong pressure fluctuation, wave rolling phenomenon, water aerated flow, cavitations of hydraulic structures, and so on.
Spillway tunnel is one of the most easily damaged flood discharge structures because of cavitations. For this, our predecessors have done a lot of researches and found that air entrainment is one of efficient and inexpensive methods to prevent cavitations in a lot of hydropower projects (Russell 1974 and Rutschmannn & Volkart 1988). Therefore, various kinds of aeration facility will be taken into account on almost all large flood discharge spillway tunnels, such as aerator with airshaft, sudden expansion and fall aerator and so on (Boes & Hager 2003; Pegram 1999; Liu et al. 2008; Xu et al. 2008 and Wang et al. 2009). So it is of great significance to study the characteristic of the air motion in the spillway tunnel with aerators.
