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Effect of Control Section on Stepped Spillway Flow

Author(s): Michael Pfister

Linked Author(s): Michael Pfister

Keywords: Ir concentration; Broad-crested weir; Stepped spillways; Standard-crested weir; Flap-gate

Abstract: Stepped spillways typically include a standard crest profile. Few prototypes exist with other control sections, such as broad-crested weirs. Using flap-gates to control stepped spillways is not common. The present research intents to exemplarily investigate stepped chutes with a broad-crested weir or a flap-gate on the crest. Differences in the hydraulic characteristics relative to the conventional stepped chute are described. The tests indicated that the flow normally separates from the first steps downstream of the broad-crested weir, generating a free jet impinging further downstream onto the chute. The cavity formed under this jet must be aerated to avoid fluctuating flow conditions. If inserting in addition a flap-gate, distinctively longer and higher jets with reduced streamwise energy dissipation resulted, generating an intense spray at the jet impact, besides large impact forces.


Year: 2009

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