Author(s): K. Kramer; W. H. Hager; H. E. Minor
Linked Author(s):
Keywords: Ir entrainment; Air-water flow; Chute; Experiments; Free surface aeration; Hydraulics
Abstract: To avoid cavitation damage on chutes, the bottom air concentration should have a threshold value. At high head chute spillways air is added with specially designed chute aerators in addition to surface air entrainment to suppress cavitation damage. This research addresses a particular feature of chute air-water mixture flow by considering the streamwise development of mean air concentration. Two distinctly different devices for air flow generation were employed originating in significant variation of air concentration in their near fields. These include a jetbox to specify flow conditions at the chute beginning, and a chute deflector shortly downstream of it that entrained air only by jet deflection and turbulence generation. It was demonstrated that the proper chute characteristics become relevant for the far-field flow region. Based on selected experimental data collected in a relatively large chute model, a trend of mean air concentration in terms of these model chute characteristics was established. The implications of that concept are then discussed and it is proposed that additional research is needed to describe so-called uniform mixture flow characteristics in waves is also addressed and a possible experimental setup is described that might result in the information presently not yet available. chutes of definite roughness and bottom slope. The problem posed by the generation of roll
Year: 2003