Hydraulic jump in circular pipes

Abstract

Hydraulic jumps in conduits containing free surface flow have received practically no attention. This project was conducted to investigate experimentally the main features of such jumps and to obtain limits for conduit choking. The sequent depth ratio is determined in terms of the approach Froude number based on the conventional momentum approach. The lengths of the surface recirculation and aeration zones are also considered. Two different appearances of jumps are discussed and it is demonstrated that jumps with a small approach depth differ from those with a depth larger than about 30% of the conduit diameter. A choking condition is proposed for which conduits are subjected to full pipe downstream flow. Photographs are used to describe the main flow pattern. The results of this study are readily applicable for design.Key words: aeration, conduit choking, hydraulic jump, pipe flow, sequent depths.