![Sample our Economics, Finance,Business & Industry journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5931/TOC-Subject-Sample-2021-Economics-Finance-Business-Industry.jpg"})
Abstract
A spillway upgrade of the Trängslet Dam, Sweden, is planned. The existing rock chute will be converted into a stepped chute of variable width, step height, and bottom slope. Its two-phase flow features including cavitation risk were investigated in a hydraulic scale model of which the effects of step height and chute width on flow characteristics and air transport were assessed. A comparison with standard approaches for stepped chute flows indicates in general a good agreement despite the geometrical complications and the non-uniform air–water flow. Deviations were attributed to spatial flow features including junctions, shock waves, and variable chute width and slope. The cavitation performance of the chute was found to be not critical up to the design discharge, but incipient cavitation may not be excluded for the safety-check flood. Therefore, the current knowledge of two-dimensional stepped chute flow can at least be approximately adopted for more complicated chute arrangements.
Acknowledgements
The authors thank Fortum Generation AB, Borlänge, Sweden, and Sweco Infrastructure AB, Stockholm, Sweden, for the excellent collaboration within this project.
Notation
| b | = | = chute width; |
| C | = | = air concentration; |
| Cb | = | = pseudo-bottom air concentration; |
| Cm | = | = depth-averaged air concentration; |
| Cp 0.1% | = | = pressure coefficient of minimum pressure head with 0.1% probability; |
| = | = turbulent diffusivity normal to pseudo-bottom; | |
| = | = dimensionless parameter; | |
| = | = friction factor; | |
| = | = Froude number in terms of step roughness | |
| = | = Froude number; | |
| g | = | = gravity acceleration; |
| hc | = | = critical flow depth; |
| hp v | = | = relative vapor pressure head (∼10 m); |
| hpmean | = | = time-averaged measured relative pressure head; |
| hp0.1% | = | = minimum relative pressure head with 0.1% probability |
| hw | = | = equivalent clear-water depth; |
| hw u | = | = uniform equivalent clear-water depth; |
| h90 | = | = air–water mixture depth; |
| Li | = | = black water length from spillway crest to air inception point; |
| Ls | = | = step length parallel to pseudo-bottom Ls = s/sin φ; |
| Q | = | = clear-water discharge; |
| q | = | = specific discharge; |
| = | = Reynolds number | |
| Rh | = | = hydraulic radius; |
| s | = | = step height; |
| v | = | = flow velocity; |
| vc | = | = critical flow velocity regarding cavitation inception; |
| = | = Weber number | |
| z | = | = coordinate perpendicular to pseudo-bottom; |
| φ | = | = angle of chute pseudo-bottom; |
| ν | = | = kinematic fluid viscosity; |
| ρ | = | = fluid density; |
| σs | = | = fluid surface tension; |
| σ | = | = cavitation index; and |
| σc | = | = critical cavitation index. |
Notes on contributors
Nicola Lutz
Since 2010 Project manager in the Hydraulic Structures division, VAW
Project engineer in the Applied Numerical Group at VAW
2007–2010 Project and research engineer in the River Engineering division, VAW
2002–2007 Diploma in Civil Engineering (Dipl.lng.) at the Swiss Federal Institute of Technology, Zurich, CH
Jill Lucas
Since 2014 Project engineer at Hetzer, Jäckli und Partner AG
2010–2014 Project and research engineer in the Hydraulic Structures division, VAW
2010 Master in Civil Engineering at the Swiss Federal Institute of Technology, Zurich, CH
Adriano Lais
Since 2009 Occupant's representative for the technical project of the new hydraulic laboratory of VAW
Since 2006 Operation Manager of VAW
Since 2003 Head of the Hydraulic Structures Division of VAW
Since 1995 Member of the Hydraulic Structures Division of VAW
1995 Diploma in Civil Engineering (Dipl.lng.) at the Swiss Federal Institute of Technology, Zurich, CH
Robert Michael Boes
Professional activities
2009 Professor for Hydraulic Structures and Director of the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich
2007–2009 TIWAG-Tiroler Wasserkraft AG, Engineering Services Division, Innsbruck, Austria: Head of Dam Construction Group; Deputy Technical Project Manager for the Realization of the TIWAG hydropower development programme in the Tyrol; responsible designate for TIWAG dam surveillance
2002–2006 TIWAG Hydro Engineering GmbH, Innsbruck, Austria: Project Manager in the Hydraulic Engineering Division, interdisciplinary projects in hydraulic structures, hydropower, flood protection, and operations optimization
2002 TIWAG-Tiroler Wasserkraft AG, Civil Engineering Division, Innsbruck, Austria: Project Engineer in the Construction Directorate, in charge of project management in the field of hydraulic engineering, and of interdisciplinary acquisition, both nationally and internationally (e.g. Belgium, Greece, Jordan, Kazakhstan, Croatia, Turkey)
2000–2001 ETH Zurich, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), project and research engineer (post doctoral fellow) in the Hydraulic Structures division
Education
1996–2000 Doctoral Dissertation (Dr. sc. techn.) at ETH Zurich
1994–1996 Studies of Civil Engineering at the Technical University Munich, Germany; degree: Diplom-Ingenieur
1993–1994 Studies of Civil Engineering at the Ecole Nationale des Ponts et Chaussées (ENPC), Paris, France
1990–1992 Studies of Civil Engineering at RWTH Aachen University, Germany