Experiments in Fluids

, 54:1514 | Cite as

Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

Research Article

Abstract

Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5–10 % of the discharge in the draft tube cone is passing inside the vortex rope.

Keywords

Particle Image Velocimetry Particle Image Velocimetry Measurement Pressure Oscillation Draft Tube Particle Image Velocimetry Image 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

The authors would like to thank the EOS Holding for their financial support and BC Hydro for making available the reduced scale model of the Francis turbine, in particular Danny Burggraeve and Jacob Iosfin for their help. Moreover, the authors would like to acknowledge the commitment of the Laboratory for Hydraulic Machines technical staff, especially Georges Crittin, Maxime Raton and Alain Renaud.

References

  1. Alligné S, Maruzewski P, Dinh T, Wang B, Fedorov A, Iosfin J, Avellan F (2010) Prediction of a Francis turbine prototype full load instability from investigations on the reduced scale model. IOP Conf Ser Earth Environ Sci 12(1):012025Google Scholar
  2. Brennen C (1978) Bubbly flow model for the dynamic characteristics of cavitating pumps. J Fluid Mech 89(pt 2):223–240CrossRefGoogle Scholar
  3. Brennen C, Acosta A (1976) Dynamic transfer function for a cavitating inducer. J Fluids Eng Transa ASME Ser 98 1(2):182–191CrossRefGoogle Scholar
  4. Chen C, Nicolet C, Yonezawa K, Farhat M, Avellan F, Tsujimoto Y (2008) One-dimensional analysis of full load draft tube surge. J Fluids Eng Trans ASME 130(4):0411061–0411066CrossRefGoogle Scholar
  5. IEC Standards (1999) 60193: hydraulic turbines, storage pumps and pump–turbines—model acceptance tests. International Electrotechnic Commission, 2nd ednGoogle Scholar
  6. Lawson N, Guerre A, Liow JL, Rudman M (1999) Experimental and numerical comparisons of the break-up of a large bubble. Exp Fluids 26(6):524–534CrossRefGoogle Scholar
  7. Otsu N (1979) Threshold selection method from gray-level histograms. IEEE Trans Syst Man Cybern SMC 9(1):62–66MathSciNetCrossRefGoogle Scholar
  8. Pedocchi F, Martin J, Garca M (2008) Inexpensive fluorescent particles for large-scale experiments using particle image velocimetry. Exp Fluids 45(1):183CrossRefGoogle Scholar
  9. Rheingans W (1940) Power swings in hydroelectric power plants. Trans ASME 62:171–184Google Scholar
  10. Rubin S (1966) Longitudinal instability of liquid rockets due to propulsion feedback/POGO/. J Spacecr Rocket 3:1188–1195CrossRefGoogle Scholar
  11. Tsujimoto Y, Yoshida Y, Maekawa Y, Watanabe S, Hashimoto T (1997) Observations of oscillating cavitation of an inducer. J Fluids Eng Trans ASME 119(4):775–781CrossRefGoogle Scholar
  12. Willert C, Gharib M (1991) Digital particle image velocimetry. Exp Fluids 10(4):181–193CrossRefGoogle Scholar
  13. Yonezawa K, Konishi D, Miyagawa K, Avellan F, Doerfler P, Tsujimoto Y (2012) Cavitation surge in a small model test facility simulating a hydraulic power plant. Int J Fluid Mach Syst 5(4):152–160Google Scholar
  14. Young F (1989) Cavitation. McGraw-Hill Book Company, LondonGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • A. Müller
    • 1
  • M. Dreyer
    • 1
  • N. Andreini
    • 2
  • F. Avellan
    • 1
  1. 1.Laboratory for Hydraulic MachinesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
  2. 2.Environmental Hydraulics LaboratoryEcole Polytechnique Fédérale de LausanneLausanneSwitzerland

Personalised recommendations