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Prof. Dr.-Ing. Dominique Thévenin Nils Lichtenberg, M.Eng. Stephanie Müller, B.Sci. Olivier Cleynen, M.Eng. Stefan Hoerner, M.Sc. Emeel Kerikous, M.Sc.

Wann ist ein Wirbelwasserkraftwerk fischfreundlich?

Numerische Untersuchungen zum „Fischfreundlichen Wehr“

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Source: (14.09.2016) https://www.land-der-ideen.de/sites/default/files/styles/Ort_4-3_460x307/public/elected_places/2014/DSC_0627_0.JPG

What is a fish-friendly weir (FFW)?Prototype from Käppler & Pausch + Ecoligent in Bühlau

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Inletchannel

Vortexpool

Turbine

Source: (14.09.2016) http://www.efre-thueringen.de/mam/efre/projekte/fittosize__800_0_17eef5a697bf84f34be94f2cd383410f_1311_abbildung_04.jpg

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Investigating the FFW at University Magdeburg: •  Understanding: What does the flow structure look like in

the weir? •  Checking: How can we assess fish-friendliness

– even before construction? •  Optimizing: Maximize turbine efficiency (while keeping

fish-friendliness) •  Upgrading: Cascading the FFWs

?

kWh

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inlet

free surface

vortex core

CFD (Computational Fluid Dynamics) •  Principle:

•  We define the geometry, the walls, the inflow conditions… •  The computer then calculates the fluid flow based on

conservation equations for mass, momentum, energy

•  Once completed (it can take weeks! ), every detail of the flow (velocity, pressure, turbulence…) can be analyzed

🤔

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What does „fish-friendly“ mean?

Fish can swim through a device if: •  Enough space is available – geometry •  The water level is high enough - depth •  The water is not too fast – sprint (or maximal) velocity •  The water is fast enough – attraction (or minimal) velocity •  The local pressure drop is low enough – specific power

density; can be also quantified through turbulent dissipation rate

Final decision must be taken by specialists!

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Adapted Life Forms- Representative Fish

Source: Naturnaher Wasserbau – Heinz Patt

International designation Fish region

Krenal

Epi-Rhithral Upper trout region

Meta-Rhithral Lower trout region

Hypo-Rhithral Grayling region

Epi-Potamal Barb region

Meta-Potamal Bream region

Hypo- Potamal Ruffe-Flounder-region

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Assessing fish-friendliness with CFD: input data

Pos. max. EnergiedissipationBreite Höhe Mindest-Wassertiefe

(HWK_min > 2,5 * hFisch) min. Fließgeschw.

im Wanderkorridormittlere Fließgeschw.im Wanderkorridor

max. Fließgeschwindigkeitim Schlupfloch

Spezifische LeistungsdichteGrenzwerte für Fischaufstiegsanlagen und

fischpassierbare Bauwerke in Beckenbauweise

BSL_min HSL_min HWK_min vWK_min vWK_mittel vSL_max Pmax bei Q30

[m] [m] [m] [m/sec.] [m/sec.] [m/sec.] [W/m³]A B C D E F G I J K

X 1 Bachforelle Salmo trutta fario (Linné) 0,20 0,20 0,24 0,20 1,32 2,00 250X 2 Bachneunauge Lampetra planeri (Bloch) 0,20 0,20 0,24 0,20 1,32 2,00 250X 3 Groppe Cottus gobio (Linné) 0,20 0,20 0,24 0,20 1,32 2,00 250

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isch

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Dieses Tabelle ist Eigentum von ecoligent,hydropower4u und windpower4u und urheberrechtlich geschützt!

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hydraulische Bemessungvorgaben zur FFW-Anlage "Fischfreundliches Wehr", Stand: 06.09.2016

Schlupfloch

Obere Forellenregion

Wanderkorridorwiss. Name

(Basis: Tabellenwerte des Merkblattes DWA-M 509 für beckenartige Fischaufstiegsanlagen)

Fließgewässerregion Fischart

X 3 Groppe Cottus gobio (Linné) 0,20 0,20 0,24 0,20 1,32 2,00 250X 6 Elritze Phoxinus phoxinus (Linné) 0,20 0,20 0,24 0,20 1,26 1,90 225X 8 Schmerle Barbatula barbatula (Linné) 0,20 0,20 0,24 0,20 1,26 1,90 225X 14 Dreistachliger Stichling Gasterosteus aculeatus (Linné) 0,20 0,20 0,24 0,20 1,20 1,80 200X 17 Gründling Gobio gobio (Linné) 0,20 0,20 0,24 0,20 1,20 1,80 200X 18 Hasel Leuciscus leuciscus (Linné) 0,30 0,30 0,32 0,20 1,20 1,80 200X 22 Rotauge (Plötze) Rutilus rutilus (Linné) 0,30 0,30 0,32 0,20 1,20 1,80 200X 24 Aal Anguilla anguilla (Linné) 0,20 0,20 0,24 0,20 1,08 1,60 150X 43 Ukelei Alburnus alburnus (Linné) 0,20 0,20 0,24 0,20 1,08 1,60 150X 32 Flussbarsch Perca fluviatilis (Linné) 0,30 0,35 0,31 0,20 1,08 1,60 150 6X 28 Barbe Barbus barbus (Linné) 0,45 0,35 0,33 0,20 1,08 1,60 150 7X 29 Blei (Brachse) Abramis brama (Linné) 0,60 0,50 0,52 0,20 1,08 1,60 150 8

4

5

2

3

Barbenregion

Untere Forellenregion

Äschenregion

Source: DWA-M 509 überarbeitet durch Herrn Signer & ecoligent

geometry

depth

dissipation minimum velocity maximum

velocity

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Rheoactive swimming behavior: a minimum velocity is needed for the flow to be “attractive” for a fish

source: Fischaufstiegsanlagen und fischpassierbare Bauwerke (Adam)

Flow direction vm > 0.2 m/s

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Assessing fish-friendliness with CFD

Minimum (attraction) flow velocity

flow direction

with a distance to the wall of 10 cm

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Maximum velocity

flow direction

Assessing fish-friendliness with CFD

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But CFD can tell us even more!

•  How does the vortex behave in the pool? What is the position of the vortex center?

•  How deep is the vortex core? Will air get entrained?

•  How does the water level profile change when changing flow rate?

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Computational Fluid Dynamics of a single FFW -  Colored by velocity magnitude

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-  Colored by water height

Computational Fluid Dynamics of a single FFW

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Field of turbulent kinetic energy o  Regions leading to exhaustion by turbulence (stochastic

movements force the fish to stabilize itself permanently)

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Very interesting, however…

Everything has a cost! •  1simulated second of real time = 1 day of calculation

on standard PC •  Numerical and modelling errors impact CFD outcome,

in particular due to turbulence •  Hence, experimental data is needed to calibrate and

validate simulation procedure •  Simpler (and thus less expensive) analytic models may

also provide valuable insight

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What should a free-surface vortex look like?

•  A problem that has been studied theoretically for over a century

•  The opposite of CFD:an exact solution to a strongly simplified problem

•  Computing the solution:less than one second

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Einstein & Li, 1955

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Einstein & Li, 1955

vortex center vortex center

Tangential velocity Free surface air

water

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Comparison of velocity profiles

CFD

theory

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Validation by comparison with experiments: a necessary step

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Comparison with existing data

Unfortunately, only one short set of measurements published:

P. Lippitisch: Funktionskontrolle des „Fischfreundlichen Wehrs“ im Bezug auf die Fischdurchgängigkeit, Studentische Arbeit, University of Görlitz/Zittau, 2013

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Velocitydistribu6on

CFD

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Comparison of velocity profiles

CFD

theory

smoothed measurement data

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Al6tudeofthefreesurface

0 0,5 1 1,5 2 2,5 -0,2

0

0,2

0,4

0,6

0,8

1

1,2

1,4

Radius (m) W

asse

rhöh

e (m

)

DiplomathesisP.Lippitsch:“Funk7onskontrolledes“Fisch-freundlichenWehrs”imBezugaufdieFischdurchgängigkeit;UniversityofGörlitz/ZiJau;Ecoligent;February2013

measurement data

fit of measurement data

CFD

entry level

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Next steps

Much richer and more precise experimental data sets are absolutely needed!

•  Possibly on-site with the prototype in Bühlau: but depending completely on weather and environmental conditions…

•  In the Lab of TU Dresden: reproducible experiments under controlled inflow conditions are possible there. Optical access provided (clear water). And tests involving different kinds of fish, under control of biologists. Would be much better! Decision pending…

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Very useful for such measurements: autonomous measurement probes

Live data acquisition: •  Radiotransmission with 10Hz

frequency •  Computer-based acquisition

of temperature, acceleration (ó forces), pressure (ó depth)

•  No optical access needed: no problem with turbidity

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Upcoming measurement campaigns •  On-site in the prototype in

Bühlau? •  In the upcoming cascade

installation in the TU Dresden Laboratories: •  Punctual velocity probe

measurements •  Blade-impact measurements using

autonomous probes •  Local velocity/turbulence

measurements (LDA, Laser-Doppler Anemometry)

•  Large-scale velocity measurements (PIV, Particle Image Velocimetry) Photo: MDR/Robert Mönch

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Conclusions •  Fluid simulations are a complex, but very powerful tool •  Reliable CFD simulations require high-quality

experimental measurements for validation •  Results:

•  Precise, reproducible assessment of fish-friendliness based on fluid dynamics

•  Ability to characterize completely the weir and possible variations: calculate turbine power, cover wide range of volume flows, etc.

•  Opening the door for process control and turbine optimization

?

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Lehrstuhl für Strömungsmechanik und Strömungstechnik (LSS) http://www.lss.ovgu.de/ Prof. Dr-Ing. Dominique Thévenin

Financial support of BMBF within „Fluss-Strom“-initiative is gratefully acknowledged! These presentation slides contain data from: •  N. Lichtenberg, O. Cleynen, D. Thévenin: Numerical investigations of a water vortex hydropower

plant implemented as a Fish Ladder – Part I: The water vortex. In: Proceedings of the 4th IAHR Europe Congress, Liège (Belgium). 2016

•  S. Müller: Numerical Investigation of a Fish-friendly Weir with OpenFOAM. 4th OpenFOAM User Conference, Aachen. 2016