Scale effects of air entrained by hydraulic jumps within closed conduits

Abstract

While there has been a great deal of research in air entrainment at hydraulic jumps within closed conduits, limited research has specifically addressed size-scale effects. To determine the significance of these effects in closed conduits, air flow measurements were taken in four different-sized circular pipes with similar Froude numbers. Additionally, specific measurements were taken in one of the pipes with various water temperatures to identify any effects from changing fluid properties. The results indicated that the percentage of air entrainment was not affected by the pipe size if the full length of the hydraulic jump was contained within the pipe. For this condition, the data from four different pipes show that size-scale effects of air entrained into hydraulic jumps within closed conduits are negligible. However, air entrainment was significantly affected by water temperature.