Author(s): Jin-Hong Kim; Kyung-Sub Kim
Linked Author(s):
Keywords: Energy dissipation; Nappe flow; Skimming flow; Stepped drop structure; Air entrainment; Air pocket; Hydraulic jump; Recirculating vortices
Abstract: This paper deals with energy dissipations by flow characteristics of nappe flow and skimming flow at the stepped drop structure. Hydraulic analysis on the energy dissipation by the nappe flow and the skimming flow, and the relationships of the air entrainment to the hydraulic parameters were presented through the hydraulic experiments. Nappe flow occurred at low flow rates and for relatively large step height. Dominant flow features included an air pocket, a free-falling nappe impact and a subsequent hydraulic jump on the downstream step. Skimming flow occurred at larger flow rates with formation of recirculating vortices between the main flow and the step corners. Energy dissipations in both cases of nappe flow and skimming flow were proportional to the step height and were inversely proportional to the overflow depth, and were not proportional to the step slope. Energy dissipations in both cases of nappe flow and skimming flow were proportional to the step height and were inversely proportional to the overflow depth, and were not proportional to the step slope. Significant energy dissipation takes place through the maintenance of recirculating vortices and the variations of free surface water profile. Experimental values showed the similar results as the theoretical ones, but they must be verified quantitatively through further more results.
Year: 2005