Abstract
The presence of swirl is often the cause of separations and pressure fluctuations in the draft tube of hydraulic reaction turbines, in particular Francis turbines. At the design point, water turbines generally operate with little swirl entering the draft tube and no flow separations, but at off-design, at both high and low load, the flow leaving the turbine has a large swirling component. The present chapter describes a number of physical mechanisms that work to produce the pulsation. Their occurrence and impact depend mainly on the actual flow rate of the turbine, but also on the local pressure level, on the exit velocity field of the particular runner, the shape of the draft tube, and the dynamic response of the whole hydraulic circuit. In medium- and large-sized turbines, the frequency of these ‘draft tube surges,’ which are often approximately periodic, is of the order of 1 Hz, and therefore they may also produce significant electrical power swings. Given a sufficiently strong vortex flow, comparable phenomena may also occur in other locations, for example in the runner channels, or in penstock manifolds.
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References
Meldau, E. (1935). Swirling flow in rotationally symmetric cavity (in German). PhD thesis, Technical University Hannover.
Cassidy, J. J., & Falvey, H. T. (1970). Frequency and amplitude of pressure surges generated by swirling flows. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 5th Symposium (Stockholm, 1970), paper E1.
Nishi, M., Kubota, T., Matsunaga, S., & Senoo, Y. (1980). Study on swirl flow and surge in an elbow type draft tube. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 10th Symposium (Tokyo, 1980), Vol. 1, pp. 557–568.
Nishi, M., Kubota, T., Matsunaga, S., & Senoo, Y. (1984). Surging characteristics of conical and elbow-type draft tubes. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 12th Symposium (Stirling, 1984), pp. 272–283.
Rheingans, W. J. (1940). Power swings in hydroelectric power plants. Transactions of the ASME, 62, 171–184.
Ulith, P., Jaeger, E. U., & Strscheletzky, M. (1974). Contribution to clarifying the inception of nonstationary phenomena in the draft tube of high specific speed Francis turbines operating at part load. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 7th Symposium (Vienna, 1974), paper III-4.
Moody, L. F. discussion of [1].
Brennen, C. (1978). The unsteady, dynamic characterization of hydraulic systems with emphasis on cavitation and turbomachines. Joint ASME/ASCE/IAHR Symposium, Fort Collins, 1978, pp. 97–107.
Dériaz, P. (1960). A contribution to the understanding of flow in the draft tubes of Francis turbines. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 1st Symposium (Nice, 1960), paper B-1.
Doerfler, P. (1982). System oscillations excited by the Francis turbine’s part load vortex core: Mathematical modelling and experimental verification (German text, English summary). Dissertation, Technical University Vienna (Austria), October 1982.
Doerfler, P. (1982). System dynamics of the Francis Turbine Half Load Surge. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 11th Symposium (Amsterdam, 1982), Vol. 2, Paper 39.
Ruprecht, A., Helmrich, Th., Aschenbrenner, Th., & Scherer, Th. (2001). Simulation of pressure surge in a hydro power plant caused by an elbow draft tube. 10th International Meeting of the work group on the behaviour of hydraulic machinery under steady oscillatory condition, Trondheim, Norway.
Sick, M., Dörfler, P., Lohmberg, A., & Casey, M. (2002). Numerical simulations of vortical flows in draft tubes. WCCM V, Vienna, Austria, 2002.
Stein, P., Sick M., Doerfler P., White, P., & Braune, A. (2006). Numerical simulation of the cavitating draft tube vortex in a Francis turbine. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 23rd Symposium, Yokohama, Japan, 2006.
Wahl, T. L., Skinner, M. M., Falvey, H. T. (1991). The Twin Vortex Draft Tube Surge. Waterpower’91, pp. 2011–2020.
Dörfler, P., Bloch, R., Mayr, W., & Hasler, O. (1988). Vibration tests on a high-head (740 m) Francis turbine: Field tests from Häusling. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 14th Symposium (Trondheim, 1988), Vol. 2, Paper D1.
Guarga, R., Hiriart, G., Torres, J. J. (1983). Oscillatory problems at Mexico’s La Angostura plant. Water Power & Dam Construction, October 1983, pp. 33–36.
Glattfelder, A. H., Grein, H., & Huser, L. (1980). Self-excited oscillations in a hydroelectric unit. IAHR/IUTAM Symposium, Karlsruhe, 1979, Paper B11. In E. Naudascher & D. Rockwell (Ed.), Practical experiences with flow-induced vibrations. Berlin: Springer.
Gummer, J. H. (2007). Penstock resonance resulting from unstable turbine characteristics, Paper 21.01, Hydro 2007, Granada.
Doerfler, P. (1994). Observation of pressure pulsations at high partial load on a Francis model turbine with high specific speed. IAHR Work Group WG1 (The Behaviour of Hydraulic Machinery under Steady Oscillatory Conditions) 6th Meeting, Lausanne 1993, also in: Hydro-power & Dams, January 1994.
Billdal, J. T., & Holt, B. G. (2000). Three Gorges project: Review of GE energy Norway’s hydraulic design. Proceedings of the Hydraulic Machinery and Systems 20th IAHR Symposium (Charlotte, 2000).
Shi, Q. (2008). Experimental investigation of upper part load pressure pulsations for Three Gorges model turbine. IAHR 24th Symposium on Hydraulic Machinery Systems, Foz do Iguassú, October 2008.
Arpe, J., & 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, September 2002, pp. 593–602.
Rudolf, P., Pochyly, F., Hábán, V., & Koutnik, J. (2007). Collapse of cylindrical cavitating region and conditions for existence of elliptical form on cavitating vortex rope. IAHR WG (Cavitation and Dynamic Problems in Hydraulic Machinery and Systems) 2nd Meeting, Timisoara Romania, October 24–26, 2007.
Nicolet, C., Zobeiri, A., Maruzewski, P., & Avellan, F. (2010). On the upper part load vortex rope in Francis turbine: Experimental investigation. 25th IAHR Symposium on Hydraulic Machinery and Cavitation, Timisoara 2010.
Kirschner, O., Ruprecht, A., & Göde, E. (2009). Experimental investigation of pressure pulsation in a simplified draft tube, Proceedings of the 3rd Meeting IAHR Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Brno 2009, Paper B1.
Strohmer, F. (1975). Investigation of the operational behaviour of a Francis turbine with high specific speed below best efficiency point (in German). Dissertation, Technical University Vienna (Austria), April 1975.
Fisher, R. K., Palde, U., & Ulith, P. (1980). Comparison of draft tube surging of homologous scale models and prototype Francis turbines. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 10th Symposium (Tokyo, 1980), Vol. 1, pp. 541–556.
Pulpitel, L. (1985). Low frequency pressure oscillations in hydraulic systems with a pump turbine. IAHR Work Group WG1 (The Behavior of Hydraulic Machinery under Steady Oscillatory Conditions) 2nd Meeting, Mexico City, 1985.
Flemming, F., Foust, J., Koutnik, J., & Fisher, R. K. (2008). Overload surge investigation using CFD data. IAHR 24th Symposium on Hydraulic Machinery Systems, Foz do Iguassú, October 2008.
Dörfler, P., Braun, O., & Sick, M. (2001). Hydraulic stability in high-load operation: a new model and its use in Francis turbine refurbishment. Hydropower and Dams, (4), 84–88.
Dörfler, P. K. (2009). Evaluating 1D models for vortex-induced pulsation in Francis turbines. Proceedings of the 3rd Meeting IAHR Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Brno 2009, Paper F3.
Dörfler, P. K., Keller, M., & Braun, O. (2010). Full-load vortex dynamics identified by unsteady 2-phase CFD. 25th IAHR Symposium on Hydraulic Machinery and Cavitation, Timisoara 2010.
Purdy, C. C. (1979). Reducing power swings at Tarbela’s turbines. Water Power and Dam Construction, April 1979, pp. 23–27.
Arzola, F., Azuaje, Z., Zambrano, P., & Gulbrandsen, G. (2006). Undesired power oscillations at high load in large Francis Turbines. Experimental study and solution. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 23rd Symposium, Yokohama, Japan, 2006.
Lowys P. Y., Doyon J., Couston M., & Vuillerod G. (2001). Dynamic behaviour of low head Francis turbines. 10th International Meeting of the Work Group on the Behaviour of Hydraulic Machinery Under Steady Oscillatory Conditions, Trondheim, Norway, June 26–28, 2001.
Lowys P.-Y., Deniau J.-L., Gaudin E., Leroy P., Djatout M., (2006) On-Board Model Runner Dynamic Measurements, Hydrovision, Portland.
Coutu A., Monette C., Gagnon M., (2007) Life Assessment of Francis Runners Using Strain Gage Site Measurements, Waterpower XV, Chattanooga, TN, July 23-26, 2007.
Doerfler, P., Lohmberg, A., et al. (2003). Investigation of pressure pulsation and runner forces in a single-stage reversible pump turbine model. IAHR Work Group WG1 (The Behavior of Hydraulic Machinery under Steady Oscillatory Conditions) 11th Meeting, Stuttgart 2003.
ISO 7919 Mechanical vibration—Evaluation of machine vibration by measurements on rotating shafts Part 1: General guidelines Part 5: Machine sets in hydraulic power generating and pumping plants.
Klein, J., et al. (1976). Investigation on vibrations of a large penstock, on the sources of their excitation and on getting them under control. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 8th Symposium (Leningrad, 1976), paper I-3.
Gibberd, J. J. (1997). Diagnosis and solution of severe hydro-mechanical vibrations following the upgrading of a 30 MW UK hydro station. Conference on Refurbishment and Upgrading of Hydro Plants, October 1997, pp. 25–38.
Koutník, J., Nicolet, Ch., Schohl, G. A., & Avellan, F. (2006). Overload event in a pumped-storage power plant. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 23rd Symposium (Yokohama, 2006).
Pulpitel, L., Koutnik, J., & Skotak, A. (1998). Natural air admission of a deep submerged pump turbine. IAHR Work Group WG1 (The Behavior of Hydraulic Machinery under Steady Oscillatory Conditions) 9th Meeting, Brno 1999, paper A5, also in: Hydro Vision’98.
Skotak, A., & Pulpitel, L. (1997). Behaviour of a Kaplan turbine model operating under off-cam conditions for a wide range of load. IAHR Work Group WG1 (The Behavior of Hydraulic Machinery under Steady Oscillatory Conditions) 8th Meeting, Chatou 1997, paper G-1.
Wobornik, A. (1967). Observations downstream of Francis turbines with back pressure (in German). EuM, 84(12), 488–493.
IEC 60193 Hydraulic turbines, storage pumps and pump-turbines—Model acceptance tests, Ed. 2.0, 1999–11.
Jacob, T., Prénat, J.-E. (1996). Francis turbine surge: discussion and data base. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 18th Symposium (Valencia, 1996), pp. 855–864.
Tadel, J., Maria, D. (1986). Analysis of dynamic behaviour of a hydroelectric installation with a Francis turbine. 5th International Conference on Pressure Surges, BHRA (Hannover, 1986), Paper G1, pp. 169–176.
Biela, V. (1998). Draft tube fins. IAHR Section on Hydraulic Machinery and Cavitation, 19th Symposium (Singapore, 1998), pp. 454–461.
Rocha, G., Sillos, A. (1982). Power swing produced by hydropower units. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 11th Symposium (Amsterdam, 1982), Vol. 2, Paper 44.
Lecher, W., Baumann, K. (1968). Francis turbines at part-load with high back-pressure. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 4th Symposium (Lausanne, 1968), Paper B-4.
Nakanishi, K., Ueda, T. (1964). Air supply into draft tube of Francis turbine. Fuji Electric Review, 10(3), pp. 81–91.
Harshbarger, E. D., March, P. A., Vigander, S. (1984). The effect of hydro turbine air venting on generating efficiency, dissolved oxygen uptake, and turbine vibrations. Tennessee Valley Authority, Water Systems Development Branch, Rept. WR28-1-600-107, March 1984.
Papillon, B., Sabourin, M., Couston, M., Deschênes, C. (2002). Methods for air admission in hydroturbines. 21th IAHR Symposium on Hydraulic Machinery and Systems, Lausanne, September 9–12, 2002.
Doerfler, P. (1986). Design criteria for air admission systems in Francis turbines. IAHR Section Hydraulic Machinery, Equipment, and Cavitation, 13th Symposium (Montreal, 1986), Vol. I, Paper 8.
Papillon, B., St.-Hilaire, A., Lindstrom, M., Sabourin, M. (2004). Analysis of Francis head cover pressure and flow behavior inside runner cone. Hydro Vision 2004, Montréal, QC, August 15–18, 2004.
Malamet, S. (1962). Aeration of the turbines in the pumped storage plant Geesthacht (in German). Elektrizitätswirtschaft 61, No. 8, 20-03-1962.
Ruprecht, A., Helmrich, Th., Buntic, I. (2003). Very large eddy simulation for the prediction of unsteady vortex motion. Conference on Modelling Fluid Flow (CMFF’03). 12th International Conference on Fluid Flow Technologies, Budapest, September 2003.
Hoffmann, H., Roswora, R. R., Egger, A. (2000). Rectification of the Marsyangdi Trifurcation. HydroVision 2000 (Charlotte, 2000).
Eichler, O. (1980). Vibration phenomena on hydraulic axial turbines. IAHR/IUTAM Symposium Karlsruhe, 1979, Paper B3. In E. Naudascher & D. Rockwell (Ed.), Practical experiences with flow-induced vibrations. Berlin: Springer.
Pulpitel, L. (1993). The dynamic behaviour of a Kaplan turbine operating under non-standard conditions. IAHR Work Group WG1 (The Behaviour of Hydraulic Machinery under Steady Oscillatory Conditions) 6th Meeting, Lausanne 1993.
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Dörfler, P., Sick, M., Coutu, A. (2013). Low-Frequency Phenomena in Swirling Flow. In: Flow-Induced Pulsation and Vibration in Hydroelectric Machinery. Springer, London. https://doi.org/10.1007/978-1-4471-4252-2_2
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DOI: https://doi.org/10.1007/978-1-4471-4252-2_2
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