Hydraulic Characteristics of Labyrinth Weirs
Hydraulic Characteristics of Labyrinth Weirs

Author: Corwin M. Willmore

Publisher:

Published: 2004

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

Primarily, half-round crest labyrinth weirs were tested in this study with the side leg angle (a) ranging between 7 to 35 degrees. Historical data was primarily limited to quarter-round data. This study presents data and equations for estimating the discharge coefficient for labyrinth weirs with both half-round, quarter-round, and two Ogee-type crest weir shapes . A method is presented for comparing the flow capacity between weirs in order to determine the most efficient weir at a given Ht/P. For a labyrinth weir with the crest shape,# of cycles (N), and the cycle width (w) held constant, the discharge coefficient (Cct) decreases with decreasing side angle (a). Based on those same geometric constraints the weir length increases with decreasing side angle (a). The dimensionless parameter Cct*LJIW (which when multiplied by 73fig H,312 gives the flow per unit width) was used to evaluate the relative discharge capacity between labyrinth weirs. The results from this study show that at low (Hr!P) values and a side leg angle of 7 and 8 degrees, an Ogee-type crest will pass more flow than a half-round crest which will pass more flow than a quarter-round crest. The effects of nappe conditions for half-round crest weirs were determined and documented for the configurations tested. The use of centerline length (L3) is used in this study over the use of the effective length (L) presented in the research. Modifications are applied to the Tullis et al. (1995) design procedure. The effect of uniform sediment deposition upstream of a labyrinth weir was tested to determine the effect it had on the discharge coefficient Cct. Both level and ramped approach conditions to a labyrinth weir apron were tested and compared . A review of literature covering previous design procedures, and laboratory tests is presented .

Hydraulic Design of Labyrinth Weirs
Hydraulic Design of Labyrinth Weirs

Author: Henry T. Falvey

Publisher: American Society of Civil Engineers

Published: 2003-01

Total Pages: 162

ISBN-13: 9780784406311

DOWNLOAD EBOOK

A labyrinth weir is a series of duckbill spillways for controlling the flow of water over a dam or channel. This slim volume compares the crest shapes used on weirs, identifies considerations for designing downstream chutes and dealing with sedimentation, explores general guidelines for parameter se

Labyrinth and Piano Key Weirs
Labyrinth and Piano Key Weirs

Author: Sébastien Erpicum

Publisher: CRC Press

Published: 2011-05-10

Total Pages: 314

ISBN-13: 0203804066

DOWNLOAD EBOOK

Labyrinth spillways are almost as old as dam engineering. In spite of the fact that they appear as a very good technical-economical compromise, only 0.1% of large dams are equipped with such weirs. The main reason for this is that traditional labyrinth weirs usually cannot be installed on top of concrete gravity dams as they require a large foundat

Labyrinth and Piano Key Weirs II
Labyrinth and Piano Key Weirs II

Author: Sébastien Erpicum

Publisher: CRC Press

Published: 2013-10-21

Total Pages: 314

ISBN-13: 113800085X

DOWNLOAD EBOOK

Dam engineering is currently experiencing a strong revival of labyrinth oriented weirs. Labyrinth weirs, with a repetitive constructional character and an increased specific discharge capacity, are a very good technical-economical compromise. The concept of Piano Key Weir (PKW), with alveoli developed in overhangs from a reduced support area, enables the installation of non-linear crests at the top of concrete dams. As a result it eliminates the main drawback of classical labyrinth weirs, and enables their use to rehabilitate numerous existing dams. Since the first implementation of piano key weirs by Electricité de France on Goulours dam (France) in 2006, at least eight PKWs have been built in France, Vietnam and Switzerland. Their operation over a few years has already provided the first prototype data. Other projects are under study, construction or planning in varied countries. On another hand, research programs are under progress all over the world. Following a first edition in 2011, Labyrinth and Piano Key Weirs II – PKW 2013 collects up-to-date contributions from people with various backgrounds, from engineers and researchers to academics. Summarizing the last developments on labyrinth oriented weirs, the book constitutes the state-of-the-art in research and application of piano key weir solutions, and will be invaluable to professionals and scientists interested in Dams Engineering.

Labyrinth Weirs
Labyrinth Weirs

Author: Brian Mark Crookston

Publisher:

Published: 2010

Total Pages: 222

ISBN-13:

DOWNLOAD EBOOK

Labyrinth weirs are often a favorable design option to regulate upstream water elevations and increase flow capacity; nevertheless, it can be difficult to engineer an optimal design due to the complex flow characteristics and the many geometric design variables of labyrinth weirs. This study was conducted to improve labyrinth weir design and analyses techniques using physical-model-based data sets from this and previous studies and by compiling published design methodologies and labyrinth weir information. A method for the hydraulic design and analyses of labyrinth weirs is presented. Discharge coefficient data for quarter-round and half-round labyrinth weirs are offered for 6° sidewall angles 35°. Cycle efficiency is also introduced to aid in sidewall angle selection. Parameters and hydraulic conditions that affect flow performance are discussed. The validity of this method is presented by comparing predicted results to data from previously published labyrinth weir studies. A standard geometric design layout for arced labyrinth weirs is presented. Insights and comparisons in hydraulic performance of half-round, trapezoidal, 6° and 12° sidewall angles, labyrinth weir spillways located in a reservoir with the following orientations are presented: Normal, Inverse, Projecting, Flush, Rounded Inlet, and Arced cycle configuration. Discharge coefficients and rating curves as a function of HT/P are offered. Finally, approaching flow conditions and geometric similitude are discussed; hydraulic design tools are recommended to be used in conjunction with the hydraulic design and analysis method. Nappe aeration conditions for trapezoidal labyrinth weirs on a horizontal apron with quarter- and half-round crests (6° sidewall angle 35°) are presented as a design tool. This includes specified HT/P ranges, associated hydraulic behaviors, and nappe instability phenomena. The effects of artificial aeration (a vented nappe) and aeration devices (vents and nappe breakers) on discharge capacity are also presented. Nappe interference for labyrinth weirs is defined; the effects of nappe interference on the discharge capacity of a labyrinth weir cycle are discussed, including the parameterization of nappe interference regions to be used in labyrinth weir design. Finally, the applicability of techniques developed for quantifying nappe interference of sharp-crested corner weirs is examined.

Labyrinth and Piano Key Weirs III
Labyrinth and Piano Key Weirs III

Author: Sébastien Erpicum

Publisher: CRC Press

Published: 2017-04-11

Total Pages: 288

ISBN-13: 1351687824

DOWNLOAD EBOOK

Since the first implementation by Electricité de France on the Goulours dam (France) in 2006, the Piano Key Weir has become a more and more applied solution to increase the discharge capacity of existing spillways. In parallel, several new large dam projects have been built with such a flood control structure, usually in combination with gates. Today, more than 25 Piano Key Weirs are in operation or under construction all over the world. More than 15 years of research and development have enabled detailed investigations of the hydraulic and structural behaviour of the Piano Key Weir complex structure and have provided more and more accurate design equations. Following the proceedings of the first two workshops held in Liege (Belgium – 2011) and Paris (France – 2013), Labyrinth and Piano Key Weirs III collects the contributions presented by people with varied background, from researchers to practitioners, at the 3rd International Workshop on Labyrinth and Piano Key Weirs - PKW 2017 (22-24 February 2017, Qui Nhon, Vietnam). The papers, reviewed and accepted by an International Scientific Committee, summarize the current state-of-the-art on Piano Key Weirs from a theoretical to a practical point of view, and present most of the main projects in operation or under construction. Labyrinth and Piano Key Weirs III is thus a reference for students, practitioners and researchers interested in Dams Engineering.

Hydraulic Design of Side Weirs
Hydraulic Design of Side Weirs

Author: R. W. P. May

Publisher: Thomas Telford

Published: 2003

Total Pages: 164

ISBN-13: 9780727731678

DOWNLOAD EBOOK

Side weirs are widely used to divert or discharge flows from reservoirs, rivers, artificial channels and sewers. The hydraulic behaviour of this type of weir is complex and difficult to predict accurately using simple methods and the diversity of applictions of side weirs has the potential to complicate guidance. This manual covers the fundamental hydraulic principles and discusses the practical design issues separately for each main strcuture type.

Hydraulic and Dynamic Assessment of Triangular Labyrinth Weirs and Wier-pool Type Fishways
Hydraulic and Dynamic Assessment of Triangular Labyrinth Weirs and Wier-pool Type Fishways

Author: Shahram Dizabadi

Publisher:

Published: 2019

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

The hydraulic performance of traditional labyrinth weirs has been extensively studied in the literature. The research outcomes indicated that labyrinth weirs have many hydraulic advantages to pass more flow with a constant water head which reduces the construction cost and improve flood prevention. In this study, a series of laboratory experiments was conducted to test a new weir design based on a classical triangular labyrinth weir. A square pool was added to the vertex of a triangular labyrinth weir in two different directions to form two new designs named as labyrinth weirs with upstream and downstream pools. Detailed velocity and turbulence measurements were conducted using an Acoustic Doppler Velocimetry (ADV) probe to investigate the flow dynamics and turbulence characteristics of the new design in both free and submerged flow conditions. The ability of using a series of the newly design weirs as a fish passage was tested by constructing a series of weirs with different weir spacing. The upstream flow velocities in three directions and the mean and the turbulent kinetic energies (TKE) were measured with the ADV probe. The mean velocity and the turbulent kinetic energy distribution indicated that the maximum range occurred in the corner of the main sidewall of the weir and the pool's sidewalls. The maximum longitudinal and vertical velocities and TKE for the weir with the upstream pool occurred inside the pool, whereas the maximum lateral velocity located in the vicinity of the main sidewall of the weir. In addition, the lateral velocity in the labyrinth weir with the upstream pool changed to the elevation equal to 70% of the upstream water level.