An experimental study of air–water flows in hydraulic jumps on flat slopes

Abstract

Hydraulic jumps are characterized by three-dimensional motions, air entrainment and energy dissipation. While extensive air–water flow research has been conducted for classical hydraulic jumps, the air–water flow properties in hydraulic jumps on slopes remain widely unexplored. New air–water flow experiments were conducted of Type B and D jumps for slopes of 1.25°, 2.5° and 5°. Comparative analyses of the sloped jumps with classical hydraulic jumps for the same Froude and Reynolds numbers showed that hydraulic jumps on slopes were more stable. Close similarities in aeration and energy dissipation performances were found between the classical hydraulic jumps and Type B jumps while Type D jumps showed lower energy dissipation efficiency and aeration. Combining the observations of flow aeration and stability, the present results suggested that a Type B jump may be an optimum hydraulic jump achieving large energy dissipation while providing increased jump toe stability.