92 research outputs found
Geometric parameters influence on Piano Key Weir hydraulic performances
The Piano Key Weir is a recent evolution of the traditional labyrinth weir. Thanks to a reduced foot print, this nonlinear weir can be placed on the top of gravity dams. The Piano Key Weir geometry involves a large number of geometric parameters. Several experimental studies have been carried out to investigate the main geometric parameters influencing the weir hydraulic efficiency and to define their optimal value. In this paper, the experimental data gathered at the University of Liege are re-examined to show how the weir height, the keys widths and the overhangs positions influence, for a given crest length magnification ratio, the weir discharge capacity. The theoretical rating curve of a standard linear weir is considered for comparison. The analysis highlights that the keys widths and overhangs lengths ratios influence significantly the Piano Key Weir efficiency, but less than the weir height. Considering the above mentioned results, a cost efficient design proposed in the literature is also proved to be close to the hydraulic optimum
Management of Occupational Manganism: Consensus of an Experts' Panel
Studies and Research Projects / Report R-417, Montréal, IRSST http://www.irsst.qc.ca/en/_publicationirsst_100134.html
(Lucchini R was a member of the Expert Panel
prediction of mean and turbulent kinetic energy in rectangular shallow reservoirs
AbstractShallow rectangular reservoirs are common structures in urban hydraulics and river engineering. Despite their simple geometries, complex symmetric and asymmetric flow fields develop in such reservoirs, depending on their expansion ratio and length-to-width ratio. The original contribution of this study is the analysis of the kinetic energy content of the mean flow, based on UVP velocity measurements carried throughout the reservoir in eleven different geometric configurations. A new relationship is derived between the specific mean kinetic energy and the reservoir shape factor. For most considered geometric configurations, leading to four different flow patterns, the experimentally observed flow fields and mean kinetic energy contents are successfully reproduced by an operational numerical model based on the depth-averaged flow equations and a two-length-scale k- turbulence closure. The analysis also highlights the better performance of this depth-averaged k- model compared to an algebraic turbu..
Physical Modeling of an Aerating Stepped Spillway
To mitigate the negative effects on the water quality in the downstream river of a projected large dam, and in particular to increase the dissolved oxygen concentration during low flow periods within the first 10 years of dam operation, an aerating weir has been designed and tested on a physical model at the Laboratory of Engineering Hydraulics (HECE) of the Liege University. The design of the structure has been done considering data from the literature. The selected solution is a 3 m high stepped spillway designed to operate in nappe flow conditions within the range of design discharges (25 – 100 m³/s). To validate the design, a physical model representing a section of the weir at a 1:1 scale has been built and operated in the laboratory. Chemical dissolved oxygen removal technique has been applied upstream of the model to be able to measure the weir aerating efficiency. The physical model results show that the proposed structure is able to maintain, in the range of discharge in the river from 25 to 100 m³/s, a minimum 5 mg/l oxygen concentration downstream, whatever the upstream oxygen concentration. The paper presents the design process of the weir, the scale model features and the results of the validation tests on the physical model. The prototype construction will take place in 2017 and the water quality will be monitored
Statistics of the main purse seine fleets fishing in the Indian Ocean (1981-2008).
This document presents a summary of the statistics of French, Spanish, Italian, Seychelles
and EU related NEI purse seine fleets fishing in the Indian Ocean since 1981: effort, catch by
species and fishing type (log and free swimming schools), catch per unit of effort, sampling
and mean weights for the main species.
Since 2002, data from the European fleet (France and Spain) are collected within the
framework of the EU “Data Collection Regulation” (DCR, Reg. 1543/2000 and 1639/2001),
followed in 2008 by the “Community framework for the collection, management and use of
data in the fisheries sector and support for scientific advice regarding the Common Fisheries
Policy” (DCF, Reg 199/2008 and 665/2008). Data from other fleets are collected by SFA
(Seychelles Fishing Authority).
Data processing (species composition and size distribution) is done collectively for the whole
fishery
Statistics of the main purse seine fleets fishing in the Indian Ocean (1981-2010).
This document presents a summary of the statistics of French, Spanish, Italian, Seychelles
and EU related NEI purse seine fleets fishing in the Indian Ocean since 1981: effort, catch by
species and fishing type (log and free swimming schools), catch per unit of effort, sampling
and mean weights for the main species.
Since 2002, data from the European fleet (France and Spain) are collected within the
framework of the EU “Data Collection Regulation” (DCR, Reg. 1543/2000 and 1639/2001),
followed in 2008 by the “Community framework for the collection, management and use of
data in the fisheries sector and support for scientific advice regarding the Common Fisheries
Policy” (DCF, Reg 199/2008 and 665/2008). Data from other fleets are collected by SFA
(Seychelles Fishing Authority).
Data processing (species composition and size distribution) is done collectively for the whole
fishery
Exchange between drainage systems and surface flows during urban flooding: Quasi-steady and dynamic modelling in unsteady flow conditions
The accurate modelling of urban flooding constitutes an integral part of flood risk assessment and management in residential and industrial areas. Interactions between drainage networks and surface runoff flows are commonly modelled based on weir/orifice equations; however, this approach has not been satisfactorily validated in unsteady flow conditions due to uncertainties in estimating the discharge coefficients and associated head losses. This study utilises experimental data of flow exchange between the sewer flow and the floodplain through a manhole without a lid to develop two alternate approaches that simulate this interaction and describe the associated exchange flow. A quasi-steady model links the exchange flow to the total head in the sewer pipe and the head losses in the sewer and the manhole, whilst a dynamic model takes also into account the evolution of the water level within the manhole at discrete time steps. The developed numerical models are subsequently validated against large-scale experimental data for unsteady sewer flow conditions, featuring variable exchange to the surface. Results confirmed that both models can accurately replicate experimental conditions, with improved performance when compared to existing methodologies based only on weir or orifice equations
Technical note: Laboratory modelling of urban flooding: strengths and challenges of distorted scale models
Laboratory experiments are a viable approach for improving
process understanding and generating data for the validation of computational
models. However, laboratory-scale models of urban flooding in street networks
are often distorted, i.e. different scale factors are used in the horizontal
and vertical directions. This may result in artefacts when transposing the
laboratory observations to the prototype scale (e.g. alteration of secondary
currents or of the relative importance of frictional resistance). The
magnitude of such artefacts was not studied in the past for the specific case
of urban flooding. Here, we present a preliminary assessment of these
artefacts based on the reanalysis of two recent experimental datasets related
to flooding of a group of buildings and of an entire urban district,
respectively. The results reveal that, in the tested configurations, the
influence of model distortion on the upscaled values of water depths and
discharges are both of the order of 10 %. This research contributes to
the advancement of our knowledge of small-scale physical processes involved in urban
flooding, which are either explicitly modelled or parametrized in urban
hydrology models.</p
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