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Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition

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Journal of The Institution of Engineers (India): Series C Aims and scope Submit manuscript

Abstract

Hydraulic turbines are operated over an extended operating range to meet the real time electricity demand. Turbines operated at part load have flow parameters not matching the designed ones. This results in unstable flow conditions in the runner and draft tube developing low frequency and high amplitude pressure pulsations. The unsteady pressure pulsations affect the dynamic stability of the turbine and cause additional fatigue. The work presented in this paper discusses the flow field investigation of a high head model Francis turbine at part load: 50% of the rated load. Numerical simulation of the complete turbine has been performed. Unsteady pressure pulsations in the vaneless space, runner, and draft tube are investigated and validated with available experimental data. Detailed analysis of the rotor stator interaction and draft tube flow field are performed and discussed. The analysis shows the presence of a rotating vortex rope in the draft tube at the frequency of 0.3 times of the runner rotational frequency. The frequency of the vortex rope precession, which causes severe fluctuations and vibrations in the draft tube, is predicted within 3.9% of the experimental measured value. The vortex rope results pressure pulsations propagating in the system whose frequency is also perceive in the runner and upstream the runner.

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Abbreviations

BEP:

Best efficiency point

D:

Diameter of runner, m

GVO:

Guide vane’s opening, degree

FFT:

Fast Fourier transform

f:

Observed frequency, Hz

fn :

Runner rotational frequency, Hz

f*:

Normalised frequency, minus

frh :

Rheingans (vortex rope) frequency, Hz ≡ f/3.6

g:

9.821465 m/s2, as tested and measured at NTNU

H:

Head, m

N:

Sampling length

n:

Runner speed, rev/s

nED :

Speed factor [−], \({\text{n}}_{\text{ED}} { = }\frac{\text{nD}}{{\sqrt {{\text{gH}}_{\text{M}} } }}\)

ns :

Specific speed [−], \({\text{n}}_{\text{s}} = \frac{{\left( {{\text{n}}_{\text{P}} \frac{\uppi }{180}} \right)\sqrt {{\text{Q}}_{\text{P}} } }}{{\left( {2{\text{gH}}_{\text{P}} } \right)^{{\frac{3}{4}}} }}\)

Δp:

Pressure difference across the turbine, Pa

\({\tilde{\text{p}}}\) :

Acquired pressure signal, kPa

\({\bar{\text{p}}}\) :

Mean pressure, kPa

\({\text{p}}_{{}}^{ *}\) :

Fluctuating pressure, kPa

p:

Pressure, kPa, harmonic order (1, 2,…)

P:

Power, MW

Q:

Flow rate, m3/s−1

qED :

Discharge factor [−], \({\text{q}}_{\text{ED}} { = }\frac{\text{Q}}{{{\text{D}}^{2} \sqrt {{\text{gH}}_{\text{M}} } }}\)

R:

Runner inlet radius, m

GVO:

Guide vane’s opening, degree

RSI:

Rotor stator interactions

RVR:

Rotating vortex rope

TS:

Time step

TKE:

Turbulence kinetic energy

t:

Time, s

UPW:

Upwind

X:

Discrete quantity

\(\overline{\text{X}}\) :

Average value

λ:

Wavelength, m

α:

Angular vane/blade position, degree

ω:

Angular velocity, rad/s

ηh :

Hydraulic efficiency, %

References

  1. C. Trivedi, B. Gandhi, M.J. Cerventes, Effect of transients on Francis turbine runner life: a review. J. Hydraul. Res. (2013). doi:10.1080/00221686.2012.732971

    Article  Google Scholar 

  2. Y.Z. Liu, H.P. Chen, H.S. Koyama, Joint investigation of rotating flow with vortex breakdown using CFD, visualization and LDV. J. Hydrodyn. 17(4), 455–458 (2005)

    Google Scholar 

  3. C. Trivedi, M.J. Cerventes, B. Gandhi, O.G. Dahlhaug, Experimental and numerical studies for a high head francis turbine at several operating points. J. Fluids Eng. 135(11), 111102 (2013). doi:10.1115/1.4024805

    Article  Google Scholar 

  4. F-J. Wang, X-Q. Li, J-M. Ma, M. Yang, Experimental investigation of characteristic frequency in unsteady hydraulic behaviour of a large hydraulic turbine. J. Hydrodyn. 21(1), 12–19 (2009)

    Article  Google Scholar 

  5. H. Keck, M. Sick, Thirty years of numerical flow simulation in hydraulic turbomachines. Acta Mech. 201, 211–229 (2008). doi:10.1007/s00707-008-0060-4

    Article  MATH  Google Scholar 

  6. X-B. Liu, Y-Z. Zeng, Numerical prediction of vortex flow in hydraulic turbine draft tube for LES. J. Hydrodyn. Ser. B 17(4), 448–454 (2005)

    MATH  Google Scholar 

  7. H. Brekke, A Review on Oscillatory Problems in Francis Turbine. New Trends in Technologies: Devices, Computer, Communication and Industrial Systems. ed. by Meng Joo Er. A review on work on oscillatory problems in Francis turbines (2010) pp. 217–232

    Google Scholar 

  8. C. Nicolet, Hydroacoustic Modelling and Numerical Simulation of Unsteady Operation of Hydroelectric Systems, PhD thesis No 3751. ÉcolePolytechniqueFédérale de Lausanne (2007)

  9. T. Staubli, F. Senn, M. Sallaberger, Instability of Pump-Turbines during Start-up in the Turbine Mode (Hydro, Ljubljana, 2008)

    Google Scholar 

  10. Y.X. Xiao, Z. Wang, Z. Yan, Experimental and numerical analysis of blade channel vortices in a francis turbine runner. Int. J. Comput. Aided Eng. Softw. 28(2), 154–171 (2011)

    Article  Google Scholar 

  11. V. Hasmatuchi, M. Farhat, S. Roth, F. Botero, F. Avellan, Experimental evidence of rotating stall in a pump-turbine at off-design conditions in generating mode. ASME J. Fluids Eng. 133(5), 051104, 1–8, doi:10.1115/1.4004088 (2011)

  12. A. Zobeiri, J-L. Kueny, M. Farhat, M. F. Avellan, Pump-turbine rotor-stator interactions in generating mode: pressure fluctuation in distributor channel. 23rd IAHR Symposium, October 2006, Yokohama, Japan,  1–10 (2006)

  13. R-K. Zhang, et al., Characteristics and control of the draft-tube flow in part-load francis turbine. ASME J. Fluids Eng. 131(2), 021101, 1–9, doi:10.1115/1.3002318 (2009)

  14. A. Ruprecht, Simulation of vortex rope in turbine draft tube. Proceedings of Hydraulics Machinery Systems. 21st IAHR symposium, Lausanne (2002)

  15. A.V. Minakov, D.V. Platonov, A.A. Dekterev, A.V. Sentyabov, A.V. Zakharov, The numerical simulation of low frequency pressure pulsations in the high-head Francis turbine. Comput. Fluids 111, 197–205 (2015), doi:10.1016/j.compfluid.2015.01.007

    Article  MATH  Google Scholar 

  16. C. Nicolet, et al., Methodology for Risk Assessment of Part Load Resonance in Francis Turbine Power Plant. IAHR International Meeting of WG on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Barcelona, Spain, 1–16 (2006)

  17. M. J. Cerventes, U. Andersson, H. M. Lövgren, Turbine-99 Unsteady Simulations—Validation. IOP Conference Series: Earth and Environmental Science, Vol. 12(1), 012014, 1–10, doi:10.1088/1755-1315/12/1/012014 (2010)

  18. R. Susan-Resiga, G.D. Ciocan, I. Anton, F. Avellan, Analysis of the swirling flow downstream a francis turbine runner. ASME J. Fluids Eng. 128(1), 177–189 (2005), doi:10.1115/1.2137341

    Article  Google Scholar 

  19. O. I. Buntic, S. Dietze, A. Ruprecht, Numerical Simulation of the Flow in Turbine-99 Draft Tube. Turbine-99 III, Proceedings of the Third IAHR/EROCOFTAC Workshop on Draft Turbine Flow, Porjus, Sweden (2005)

  20. H. Wallimann, R. Neubauer, Numerical study of a high head Francis turbine with measurements from the Francis-99 project. J. Phys. Conf. Ser. 579(1), 012003 (2015), doi:10.1088/1742-6596/579/1/012003

    Article  Google Scholar 

  21. J. Wu, K. Shimmei, K. Tani, K. Niikura, J. Sato, CFD-based design optimization for hydro turbines. ASME J. Fluid Eng. 129(2), 159–168 (2007), doi:10.1115/1.2409363

    Article  Google Scholar 

  22. G.D. Ciocan, M.S. Iliescu, T.C. Vu, B. Nennemann, F. Avellan, Experimental study and numerical simulation of the FLINDT draft tube rotating vortex. ASME J. Fluids Eng. 129(2), 146–158 (2007). doi:10.1115/1.2409332

    Article  Google Scholar 

  23. T. Staubli, D. Meyer, Draft Tube Calculations. Turbine 99, EROCOFTAC/IAHR Workshop on Draft Tube Flow. Porjus, Sweden (1999)

  24. C. Luis, O. D. S. Eduardo, D. D. M. Marcelo, C. P. B. J. Antonio, Assessment of Turbulence Modelling for CFD Simulations into Hydroturbines: Spiral Casing. 17th International Mechanicsl Engineering Congress (COBEM), Sao Paulo, Brazil (2003)

  25. C. Widmer, T. Staubli, N. Ledergerber, Unstable characteristics and rotating stall in turbine brake operation of pump-turbines. ASME J. Fluids Eng. 133(4), 041101 (2011). doi:10.1115/1.4003874

    Article  Google Scholar 

  26. P. Mossinger, R. Jester-Zurker, A. Jung, Investigation of different simulation approaches on a high-head Francis turbine and comparison with model test data: Francis-99. J. Phys. Conf. Ser. 579(1), 012005 (2015). doi:10.1088/1742-6596/579/1/012005

    Article  Google Scholar 

  27. D. Jost, A. Skerlavaj, M. Morgut, P. Meznar, E. Nobile, Numerical simulation of flow in a high head Francis turbine with prediction of efficiency, rotor stator interaction and vortex structures in the draft tube. J. Phys. Conf. Ser. 579(1), 012006 (2015). doi:10.1088/1742-6596/579/1/012006

    Article  Google Scholar 

  28. R. Goyal, C. Trivedi, B. Gandhi, M.J. Cerventes, O.G. Dahlhaug, Transient pressure measurements at part load operating condition of a high head model Francis turbine. Sadhana (Springer). 41 (11), 1311–1320 (2016). doi:10.1007/s12046-016-0556-x

    Book  Google Scholar 

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Authors and Affiliations

  1. Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, India

    Rahul Goyal & Bhupendra Kumar Gandhi

  2. Norwegian University of Science and Technology, Trondheim, Norway

    Chirag Trivedi

  3. Division of Fluid and Experimental Mechanics, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden

    Michel J. Cervantes

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  1. Rahul Goyal
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  2. Chirag Trivedi
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  3. Bhupendra Kumar Gandhi
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  4. Michel J. Cervantes
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Correspondence to Bhupendra Kumar Gandhi.

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Goyal, R., Trivedi, C., Kumar Gandhi, B. et al. Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition. J. Inst. Eng. India Ser. C 99, 557–570 (2018). https://doi.org/10.1007/s40032-017-0380-z

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