An Experimental Study of the Flow in a Sharp-Heel Kaplan Draft Tube

268 Pages·2009·11.87 MB·English

by  Urban Andersson

ISSN: 1402-1544 ISBN 978-91-86233-XX-X Se i listan och fyll i siffror där kryssen är
DOCTORA L T H E S IS
Department of Applied Physics and Mechanical Engineering An Experimental Study of the Flow
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AN EXPERIMENTAL STUDY OF THE FLOW IN
A SHARP-HEEL KAPLAN DRAFT TUBE
Urban Andersson
Luleå University of Technology
Department of Applied Physics and Mechanical Engineering
Division of Fluid Mechanics
Vattenfall Research and Development AB
SE-814 26 Älvkarleby
Sweden
E-mail: [email protected]
June, 2009
Printed by Universitetstryckeriet, Luleå 2009
ISSN: 1402-1544
ISBN 978-91-86233-68-6
Luleå (cid:17)(cid:15)(cid:15)(cid:24)
www.ltu.se
ABSTRACT
This research project was originally part of a package (Turbine-99 Draft
Tube) that had a mutual goal, to improve the understanding of draft tube flow and
establish Best Practise Guidelines for simulation of draft tube flow.
The draft tube is situated after the runner in a Hydropower turbine to recover
as much of the remaining head and kinetic energy as possible before the water leaves
the runner. The case is fully turbulent, and because of the adverse pressure gradient
with risk for separation, periodic inlet conditions from the runner with different
degrees of swirl causes the draft tube flow to be difficult to predict. Therefore,
unambiguous design criterions are lacking, and the slightly contradicting
recommendations indicate that the standard rules give conservative, rather than
optimal, designs. This thesis gives some background on draft-tube flows in general
and discusses the parameters and flow conditions relevant to the Turbine-99 draft
tube in some detail.
The main goal of the thesis is to provide extensive experimental data on a
well-defined sharp-heel draft-tube flow. The data bank has served as validation data
for the simulation challenge presented by the Turbine-99 workshops in Porjus (June
1999), Älvkarleby (June 2001) and Porjus (December 2005).
The experimental data and some numerical results are also available as an
application challenge in the QNET database (managed by Ercoftac), as a validation
case for flow simulations.
The experimental data consists of visualisations, pressure measurements and
velocity measurements. These methods give a good qualitative picture of the flow
pattern in the draft tube with quantitative data at selected cross section that can be
used to validate the flow simulations. The first two workshops focused on mean
quantities of pressure and velocities; however, phase-resolved measurements have
been added to add value to the experimental data.
In addition to the experimental validation case, there is one paper that deals
with loads on the draft tube, which affect the construction lifetime. Since the
hydropower stations are expected to have a long total technical lifetime with a
number of refurbishments, these questions will grow in importance over the next
decades.
Page i
Page ii
ACKNOWLEDGMENTS
The Turbine-99 measurements were financed by the Vattenturbinteknik-
programmet, a research programme jointly financed by STEM (Swedish National
Energy Administration; originally NUTEK, Swedish National Board for Industrial
and Technical Development), ELFORSK (Joint organisation of Swedish Utilities)
and KVAERNER TURBIN AB, Sweden (today: part of Andritz).
Today Vattenturbinteknikprogrammet is a part of Svenskt Vattenkraft
Centrum (SVC), and SVC has kindly funded the writing of this thesis and the final
papers. SVC was established by the Swedish Energy Agency, Elforsk AB and
Svenska Kraftnät together with Luleå technical university, KTH - Royal Institute of
Technology, Chalmers University of Technology and Uppsala University. The
following companies also participate in SVC: Alstom Hydro Sweden, CarlBro, E.ON
Vattenkraft Sverige, Fortum Generation, GE (Sweden), Jämtkraft, Jönköping Energi,
Mälarenergi, Skellefteå Kraft, Sollefteåforsens, Statoil Lubricants, Sweco VBB,
Sweco Energuide, SweMin, Tekniska Verken i Linköping, Vattenfall Research and
Development and Vattenfall Vattenkraft, Waplans, VG Power and Öresundskraft.
The measurements in the Porjus G11 draft tube have been founded by
Vattenfall. The author is also grateful to Vattenfall for the work time granted to write
this thesis.
For the first part of the work, Professor Rolf Karlsson was the primary tutor
and mentor, and he had many valuable thoughts on the work. His unfortunate illness
and untimely death was a great loss to the fluid dynamics community and one of the
contributing reasons why this thesis had to rest for a few years.
I also have to thank Professor Michel Cervantes, who had the good sense to
convince me to take up the work again and finish this thesis. Professor Cervantes
also supervised the final portion of this thesis.
In addition, other important senior researchers have been Niklas Dahlbäck at
Vattenfall, Håkan Gustavsson at Luleå Technical University and Rickard Gebart at
ETC.
The cooperation with the division of Fluid Mechanics at Luleå University of
Technology has been a great source of inspiration, and I would like to thank Fredrik
Engström for his help with the visualisations and John Bergström and Håkan Nilsson
for their help with understanding CFD.
I would like to thank our co-workers at Vattenfall Research and
Development and especially Klas-Göran Helzenius, for his professional skills in the
turbine rig. Unfortunately, Mr Helzenius also departed prematurely and could not see
the final thesis.
Finally special thanks to my wife Sara for comments on the visual
presentation and her never failing support in spite of late nights and absent-minded
days.
Älvkarleby, June 2009
Urban Andersson
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LIST OF PAPERS
This thesis summarises the work behind the following papers:
Paper 1:
Andersson U. and Dahlbäck N. (1998) Experimental Evaluation of Draft
Tube Flow. – A Test Case for CFD-simulations, Proceedings of the XIX IAHR
Symposium on Hydraulic Machinery and Cavitation, vol1, 268-275, Singapore.
Paper 2:
Andersson U. and Karlsson R. (1999) Quality Aspects of the Turbine 99
Draft Tube experiments, Proceedings from Turbine-99 – Workshop on Draft Tube
Flow, Technical report, Luleå University of Technology, Sweden.
Paper 3:
Andersson U. (1999) Turbine 99 – Experiments On Draft Tube Flow (Test
Case T), Proceedings from Turbine-99 – Workshop on Draft Tube Flow, Technical
report, Luleå University of Technology, Sweden.
Paper 4:
Andersson U. (2001) Test Case T – Some new Results and Updates Since
Workshop I, Proceedings of Turbine-99 - Workshop 2: The second ERCOFTAC
Workshop on Draft Tube Flow, June, Älvkarleby, Luleå University of Technology,
Sweden.
Paper 5:
Andersson U. and Cervantes M. (2008) Phase-resolved Velocity
Measurements at the Draft Tube Cone of the Turbine-99 Test Case, 24th Symposium
on Hydraulic Machines and Systems, October, Foz do Iguassu, Brazil.
Paper 6:
Andersson U., Jungstedt J. and Cervantes M. (2008)A Model Experiment of
Dynamic Loads on a Draft Tube Pier, 24th Symposium on Hydraulic Machines and
Systems, October, Foz do Iguassu, Brazil.
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OTHER RELEVANT WORK
In addition to the included papers there are also two papers and two reports
found in Appendix 1 Quality and trust.
Paper A1:
Jonzén S., Hemström B. and Andersson U. (2001) Turbine 99 – Accuracy in
CFD Simulations on Draft Tube Flow, Proceedings of Turbine-99 - Workshop 2: The
second ERCOFTAC Workshop on Draft Tube Flow, June, Älvkarleby, Luleå
University of Technology, Sweden.
Paper A2:
Andersson U., Engström F., Gustavsson H. and Karlsson R. (2004) The
Turbine-99 workshops - conclusions and recommendations, Proceedings of the 22th
IAHR Symposium on Hydraulic Machinery and Systems, Paper: A11-3, Stockholm,
Sweden.
Report A1:
Andersson U. and Karlsson R. (2003) Final Application Challenge
Documentation (D30) Draft tube, Thematic Network for Quality and Trust in the
Industrial Application of CFD (QNET-CFD), EU Contract: GTC1-CT99-10030,
Report nr: D30_TA6_P27_AC6-07.
Report A2:
Karlsson R. and Andersson U. (2004) D34 Best Practice Advice for AC6-07
Draft Tube, Thematic Network for Quality and Trust in the Industrial Application of
CFD (QNET-CFD), EU Contract: GTC1-CT99-10030, Report nr:
D34_TA6_P27_AC6-07.
DIVISION OF WORK
The respondent has carried out all measurements in the Turbine-99 draft tube
(Paper 1-5) and analysis in the papers. For Paper 6 the measurements were
performed in co-operation with Jenny Jungstedt at the Hydraulic Laboratory in
Älvkarleby. The research work in the papers has been discussed in detail with the co-
authors who all came with valuable comments.
The papers presented in Appendix 1 Quality and trust contain the database
that documents the test case, and in this section, the respondent is responsible for the
measurement and presentation of the experimental data. Rolf Karlsson was the
initiating force within Quality and Trust and the Qnet-network. Paper A1 is based on
the master thesis work of Staffan Jonzén, and the respondent took part in the
tutoring, analysis and presentation of results. For the conclusions of the Turbine-99
workshops, Fredrik Engström and Håkan Gustavsson were the primary contributors.
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