The dynamics of the rotating vortex taking place in the discharge ring of a Francis turbine for partial flow rate operating conditions and cavitation free conditions is studied by carrying out both experimental flow survey and numerical simulations. 2D laser Doppler velocimetry, 3D particle image velocimetry, and unsteady wall pressure measurements are performs to investigate thoroughly the velocity and pressure fields in the discharge ring and to give access to the vortex dynamics. Unsteady RANS simulation are performed and compared to the experimental results. The computing flow domain includes the rotating runner and the elbow draft tube. The mesh size of 500,000 nodes for the 17 flow passages of the runner and 420,000 nodes for the draft tube is optimized to achieve reasonable CPU time for a good representation of the studied phenomena. The comparisons between the detailed experimental flow field and the CFD solution yield to a very good validation of the modeling of the draft tube rotating vortex and, then, validate the presented approach for industrial purpose applications.

Issue Section:
Technical Papers
Keywords:
numerical analysis, vortices, pipe flow, rings (structures), turbines, laser velocimetry, Doppler measurement, particle velocity analysis, pressure measurement, computational fluid dynamics
Topics:
Flow (Dynamics), Pressure, Vortices, Computer simulation, Computational fluid dynamics, Simulation
1.
Jacob
,
T.
, 1993, “
Evaluation sur Modèle Réduit et Prédiction de la Stabilité de Fonctionnement des Turbines Francis
,” EPFL Thesis No. 1146, Lausanne, Switzerland.
2.
Nishi
,
M.
,
Matsunaga
,
S.
,
Kubota
,
T.
, and
Senoo
,
Y.
, 1984, “
Surging Characteristics of Conical and Elbow-Type Draft Tubes
,” in
Proceedings of the 12th IAHR Symposium
, pp.
272
–
283
.
3.
Vu
,
T. C.
, and
Retieb
,
S.
, 2002, “
Accuracy Assessment of Current CFD Tools to Predict Hydraulic Turbine Efficiency Hill Chart
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
, pp.
193
–
198
.
4.
Ruprecht
,
A.
,
Maihöfer
,
M.
,
Heitele
,
M.
, and
Helmrich
,
T.
, 2002, “
Massively Parallel Computation of the Flow in Hydo Turbines
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
, pp.
199
–
206
.
5.
Ruprecht
,
A.
,
Helmrich
,
T.
,
Aschenbrenner
,
T.
, and
Scherer
,
T.
, 2002, “
Simulation of Vortex Rope in a Turbine Draft Tube
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
, pp.
259
–
266
.
6.
Scherer
,
T.
,
Faigle
,
P.
, and
Aschenbrenner
,
T.
, 2002, “
Experimental Analysis and Numerical Calculation of the Rotating Vortex Rope in a Draft Tube Operating at Part Load
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
, pp.
267
–
276
.
7.
Miyagawa
,
K.
,
Tsuji
,
K.
,
Yahara
,
J.
, and
Nombra
,
Y.
, 2002, “
Flow Instability in an Elbow Draft Tube for a Francis Pump-Turbine
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
, pp.
277
–
286
.
8.
Sick
,
M.
,
Dorfler
,
P.
,
Michler
,
W.
,
Salllaberger
,
M.
, and
Lohmberg
,
A.
, 2004, “
Investigation of the Draft Tube Vortex in a Pump-Turbine
,”
Proceedings of the 22nd IAHR Symposium on Hydraulic Machinery and Systems
,
Stockholm
,
Sweden
.
9.
IEC 60193 Standard, 1999, “
Hydraulic Turbines, Storage Pumps and Pump-Turbines-Model Acceptance Tests
,” International Electrotechnical Commission, Genève, Switzerland.
10.
Iliescu
,
M. S.
,
Ciocan
,
G. D.
, and
Avellan
,
F.
, 2002, “
3D PIV and LDV Measurements at the Outlet of a Francis Turbine Draft Tube
,” Joint U.S. ASME—European Fluids Engineering Summer Conference, Montreal, Quebec, Canada, Paper No. FEDSM2002-31332.
11.
Ciocan
,
G. D.
,
Avellan
,
F.
, and
Kueny
,
J. L.
, 2000, “
Optical Measurement Techniques for Experimental Analysis of Hydraulic Turbines Rotor-Stator Interaction
,” ASME Fluid Engineering Conference, Boston, Paper No. FEDSM2000-11056.
12.
Arpe
,
J. A.
, and
Avellan
,
F.
, 2002, “
Pressure Wall Measurements in the Whole Draft Tube: Steady and Unsteady Analysis
,”
Proceedings of the 21st IAHR Symposium on Hydraulic Machinery and Systems
,
Lausanne
,
Switzerland
.
Copyright © 2007
 by American Society of Mechanical Engineers
You do not currently have access to this content.