Hydraulics of Skimming Flow on Modeled Stepped Spillways
Publication: Journal of Hydraulic Engineering
Volume 125, Issue 5
Abstract
Two sets of models of stepped spillways of slope 1 upon 0.6 with the same crest-shape and with a range of step sizes (0.25–2.0 m on the 1:10 scale and 0.5–2.0 m on the 1:20 scale models) were built and studied. In the range of prototype unit flows considered (0.8–3.8 m2/s on the 1:10 scale models and 1.8–21.7 m2/s on the 1:20 models), the residual specific energy is independent of these step sizes, at positions where measurements were made on the spillways (from 30 m below the crest) once fully aerated skimming flow is established. The residual specific energy at the toe of a 50-m-high (or higher) stepped spillway, within the range of step heights tested, is <60% of the residual specific energy at the same level on a similar smooth spillway experiencing flows up to 20 m2/s; at these flows and at this height, the stepped spillway was found to be in equilibrium. The reduction of specific energy is lower than that expected from previous studies; these findings are likely to impact on the design of stepped spillways.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 125 • Issue 5 • May 1999
Pages: 500 - 510
History
Published online: May 1, 1999
Published in print: May 1999
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