Apron and Cutoff Wall Scour Protection for Piano Key Weirs

Piano key (PK) weirs are used in a variety of flow control structure applications, including spillway crests and open channel diversion structures. However, to the best of authors’ knowledge, structure-specific design guidance for scour mitigation is still needed. To fill this gap of knowledge, a sy...

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Bibliographic Details
Published inWater (Basel) Vol. 13; no. 17; p. 2332
Main Authors Lantz, Wyatt, Crookston, Brian Mark, Palermo, Michele
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.09.2021
Subjects
Accuracy
Cameras
Design optimization
Diversion structures
Downstream effects
Equilibrium
Floods
Flow control
Flow velocity
Fluid flow
horizontal apron
Hydraulics
local scour
Mitigation
Morphology
Open channels
Pianos
PK weir
Rivers
Scour
scour countermeasure
Scour protection
Scouring
Spheres
Spillways
vertical cutoff wall
Weirs
United States > US
Vietnam
Utah
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Summary:Piano key (PK) weirs are used in a variety of flow control structure applications, including spillway crests and open channel diversion structures. However, to the best of authors’ knowledge, structure-specific design guidance for scour mitigation is still needed. To fill this gap of knowledge, a systematic experimental campaign was conducted by testing different configurations of horizontal aprons with a cutoff wall. Protection structures were located at the toe of the PK weir. Namely, experiments were performed at large-scale to assess the effect of three apron lengths on downstream scour hole geometry under different hydraulic conditions. It was observed that a horizontal apron deflects the plunging jets originating from the PK weir, thus significantly reducing scour. Experimental evidence allowed corroboration that significant scour depth reduction occurs for an apron length 1.5 times the weir height, with longer aprons found to provide marginal benefits. Finally, also provided herein are tools to estimate the main scour characteristics and help practitioners in optimizing apron design.
ISSN:2073-4441
2073-4441
DOI:10.3390/w13172332