Suppressing the Vortex Rope Oscillation and Pressure Fluctuations by the Air Admission in Propeller Hydro-Turbine Draft Tube

Document Type : Regular Article

Authors

1 Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China

2 Huaneng Liaoning Clean Energy CO. Ltd, Shenyang, 110167, China

3 Huaneng Clean Energy Research Institute, Beijing, 102209, China

Abstract

For the purpose of automatic generation control (AGC), a portion of the propeller hydro-turbine units in China is adjusted to operate within a restricted range of 75%-85% load using computer-controlled AGC strategies. In engineering applications, it has been observed that when a propeller hydro-turbine unit operates under off-design conditions, a large-scale vortex rope would occur in the draft tube, leading to significant pressure fluctuations. Injecting air into the draft tube to reduce the amplitude of pressure fluctuations is a common practice, but its effectiveness has not been proven on propeller hydro-turbine units. In this study, a CFD model of a propeller hydro-turbine was established, and 15 cases with different guide vane openings (GVO, between 31° and 45°) under unsteady conditions were calculated and studied. Two air admission measures were introduced to suppress the vortex rope oscillation in the draft tube and to mitigate pressure fluctuations.  The reason for the additional energy loss due to air admission was then explained by the entropy production theory, and its value was quantified. This study points out that when injecting air, it is necessary to first consider whether the air will obstruct the flow in the draft tube. Finally, based on simulation and experimental data under various load conditions, pressure fluctuation analysis (based on fast Fourier transform, FFT) was conducted to assess the effectiveness of air admission measures. This study can provide an additional option for balancing unit efficiency and stability when scheduling units using an AGC strategy.

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Main Subjects

References

Ardizzon, G., Cavazzini, G., & Pavesi, G. (2014). A new generation of small hydro and pumped-hydro power plants: Advances and future challenges. Renewable and Sustainable Energy Reviews, 31, 746–761. https://doi.org/10.1016/j.rser.2013.12.043
Arispe, T. M., de Oliveira, W., & Ramirez, R. G. (2018). Francis turbine draft tube parameterization and analysis of performance characteristics using CFD techniques. Renewable Energy, 127, 114–124. https://doi.org/10.1016/j.renene.2018.04.055
Bosioc, A. I., Susan-Resiga, R., Muntean, S., & Tanasa, C. (2012). Unsteady pressure analysis of a swirling flow with vortex rope and axial water injection in a discharge cone. Journal of Fluids Engineering, 134(8). https://doi.org/10.1115/1.4007074
Cao, J., Luo, Y., Zhuang, J., Li, X., & Wang, Z. (2022). Effect of the pressure balance device on the flow characteristics of a pump-turbine. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 236(8), 1533–1543. https://doi.org/10.1177/09576509221097204
Favrel, A., Gomes Pereira Junior, J., Landry, C., Müller, A., Nicolet, C., & Avellan, F. (2018). New insight in Francis turbine cavitation vortex rope: Role of the runner outlet flow swirl number. Journal of Hydraulic Research, 56(3), 367–379. https://doi.org/10.1080/00221686.2017.1356758
Favrel, A., Lee, N., Irie, T., & Miyagawa, K. (2021). Design of experiments applied to francis turbine draft tube to minimize pressure pulsations and energy losses in off-design conditions. Energies, 14(13), Article 13. https://doi.org/10.3390/en14133894
Foroutan, H., & Yavuzkurt, S. (2014). Flow in the simplified draft tube of a francis turbine operating at partial load—part II: Control of the vortex rope. Journal of Applied Mechanics, 81(6). https://doi.org/10.1115/1.4026818
Gohil, P. P., & Saini, R. P. (2016). Numerical study of cavitation in francis turbine of a small hydro power plant. Journal of Applied Fluid Mechanics, 9(1), 357–365. https://doi.org/10.18869/acadpub.jafm.68.224.24080
Gong, R. Z., Qi, N. M., Wang, H. J., Chen, A. L., & Qin, D. Q. (2017). Entropy production analysis for s-characteristics of a pump turbine. Journal of Applied Fluid Mechanics, 10(6), 1657–1668. https://doi.org/10.29252/jafm.73.245.27675
Goyal, R., & Gandhi, B. K. (2018). Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations. Renewable Energy, 116, 697–709. https://doi.org/10.1016/j.renene.2017.10.012
Ji, L., Xu, L., Peng, Y., Zhao, X., Li, Z., Tang, W., Liu, D., & Liu, X. (2022). Experimental and numerical simulation study on the flow characteristics of the draft tube in francis turbine. Machines, 10(4), 230. https://doi.org/10.3390/machines10040230
Kock, F., & Herwig, H. (2004). Local entropy production in turbulent shear flows: A high-Reynolds number model with wall functions. International Journal of Heat and Mass Transfer, 47(10–11), 2205–2215. https://doi.org/10.1016/j.ijheatmasstransfer.2003.11.025
Krzemianowski, Z., & Kaniecki, M. (2023). Low-head high specific speed Kaplan turbine for small hydropower – design, CFD loss analysis and basic, cavitation and runaway investigations: A case study. Energy Conversion and Management, 276, 116558. https://doi.org/10.1016/j.enconman.2022.116558
Li, D., Yu, L., Yan, X., Wang, H., Shi, Q., & Wei, X. (2021). Runner cone optimization to reduce vortex rope-induced pressure fluctuations in a Francis turbine. Science China Technological Sciences, 64(9), 1953–1970. https://doi.org/10.1007/s11431-021-1867-2
Li, X., Chen, Z., Fan, X., & Cheng, Z. (2018). Hydropower development situation and prospects in China. Renewable and Sustainable Energy Reviews, 82, 232–239. https://doi.org/10.1016/j.rser.2017.08.090
Liu, X., Luo, Y., Presas, A., Wang, Z., & Zhou, L. (2018). Cavitation effects on the structural resonance of hydraulic turbines: failure analysis in a real francis turbine runner. Energies, 11(9), Article 9. https://doi.org/10.3390/en11092320
Luo, X., Ji, B., & Tsujimoto, Y. (2016). A review of cavitation in hydraulic machinery. Journal of Hydrodynamics, 28(3), 335–358. https://doi.org/10.1016/S1001-6058(16)60638-8
Luo, Y., Wang, Z., Zhang, J., Zeng, J., Lin, J., & Wang, G. (2013). Vibration and fatigue caused by pressure pulsations originating in the vaneless space for a Kaplan turbine with high head. Engineering Computations, 30(3), 448–463. https://doi.org/10.1108/02644401311314376
Mao, Z., Tao, R., Chen, F., Bi, H., Cao, J., Luo, Y., Fan, H., & Wang, Z. (2021). Investigation of the starting-up axial hydraulic force and structure characteristics of pump turbine in pump mode. Journal of Marine Science and Engineering, 9(2), Article 2. https://doi.org/10.3390/jmse9020158
Menter, F. (1993). Zonal two equation k-w turbulence models for aerodynamic flows. 23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference. American Institute of Aeronautics and Astronautics. https://arc.aiaa.org/doi/abs/10.2514/6.1993-2906
Menter, F. R. (1994). Two-equation eddy-viscosity turbulence models for engineering applications. AIAA Journal, 32(8), 1598–1605. https://doi.org/10.2514/3.12149
Muhirwa, A., Cai, W. H., Su, W. T., Liu, Q., Binama, M., Li, B., & Wu, J. (2020). A review on remedial attempts to counteract the power generation compromise from draft tubes of hydropower plants. Renewable Energy, 150, 743–764. https://doi.org/10.1016/j.renene.2019.12.141
Pasche, S., Avellan, F., & Gallaire, F. (2017). Part load vortex rope as a global unstable mode. Journal of Fluids Engineering, 139(5). https://doi.org/10.1115/1.4035640
Qian, Z. D., Li, W., Huai, W. X., & Wu, Y. L. (2012). The effect of runner cone design on pressure oscillation characteristics in a Francis hydraulic turbine. Proceedings of the Institution of Mechanical Engineers Part A-Journal of Power and Energy, 226(A1), 137–150. https://doi.org/10.1177/0957650911422865
Qian, Z., Yang, J., & Huai, W. (2007). Numerical simulation and analysis of pressure pulsation in francis hydraulic turbine with air admission. Journal of Hydrodynamics, 19(4), 467–472. https://doi.org/10.1016/S1001-6058(07)60141-3
Rajan, G. K., & Cimbala, J. M. (2016). Computational and theoretical analyses of the precessing vortex rope in a simplified draft tube of a scaled model of a Francis turbine. Journal of Fluids Engineering, 139(2). https://doi.org/10.1115/1.4034693
Shrestha, U., & Choi, Y. D. (2021). Suppression of flow instability in the Francis hydro turbine draft tube by J-groove shape optimization at a partial flow rate. Journal of Mechanical Science and Technology, 35(6), 2523–2533. https://doi.org/10.1007/s12206-021-0523-2
Sunsheng, Y., Enema Ohiemi, I., Singh, P., Li, Y., Ali, A., & Osman, F. (2023). Numerical and experimental investigation on unsteady flow and hydraulic radial force of low-head axial flow turbine. Journal of Applied Fluid Mechanics, 16(4), 830–849. https://doi.org/10.47176/jafm.16.04.1535
Yu, A., Luo, X. W., & Ji, B. (2015). Numerical simulation and analysis of the internal flow in a Francis turbine with air admission. International Symposium of Cavitation and Multiphase Flow (Iscm 2014), Pts 1-6, 72, 042047. https://doi.org/10.1088/1757-899X/72/4/042047
Yu, A., Tang, Q., Zhou, D., & Liu, J. (2021a). Numerical investigation of the energy evaluation in a Francis turbine based on an advanced entropy production model. International Communications in Heat and Mass Transfer, 129, 105755. https://doi.org/10.1016/j.icheatmasstransfer.2021.105755
Yu, A., Wang, Y. S., & Zhou, D. Q. (2021b). Vortex evolution and energy production in the blade ‎Channel of a Francis Turbine Operating at Deep Part ‎load conditions. Journal of Applied Fluid Mechanics, 14(6), 1669–1678. https://doi.org/10.47176/jafm.14.06.32435
Yu, A., Zou, Z., Zhou, D., Zheng, Y., & Luo, X. (2020). Investigation of the correlation mechanism between cavitation rope behavior and pressure fluctuations in a hydraulic turbine. Renewable Energy, 147, 1199–1208. https://doi.org/10.1016/j.renene.2019.09.096
Zhan, J., Chen, Z., Li, C., Hu, W., & Li, Y. (2020). Vortex identification and evolution of a jet in cross flow based on Rortex. Engineering Applications of Computational Fluid Mechanics, 14(1), 1237–1250. https://doi.org/10.1080/19942060.2020.1816496
Zhang, R., Mao, F., Wu, J. Z., Chen, S. Y., Wu, Y. L., & Liu, S.-H. (2009). Characteristics and control of the draft-tube flow in part-load Francis turbine. Journal of Fluids Engineering, 131(2), 021101. https://doi.org/10.1115/1.3002318
Zhou, L., Hang, J., Bai, L., Krzemianowski, Z., El-Emam, M. A., Yasser, E., & Agarwal, R. (2022). Application of entropy production theory for energy losses and other investigation in pumps and turbines: A review. Applied Energy, 318, 119211. https://doi.org/10.1016/j.apenergy.2022.119211
Zhou, X., Shi, C., Miyagawa, K., & Wu, H. (2021). Effect of modified draft tube with inclined conical diffuser on flow instabilities in Francis turbine. Renewable Energy, 172, 606–617. https://doi.org/10.1016/j.renene.2021.03.075
Zhou, X., Wu, H., & Shi, C. (2019). Numerical and experimental investigation of the effect of baffles on flow instabilities in a Francis turbine draft tube under partial load conditions. Advances in Mechanical Engineering, 11(1), 1687814018824468. https://doi.org/10.1177/1687814018824468
Zhou, X., Wu, H., Cheng, L., Huang, Q., & Shi, C. (2023). A new draft tube shape optimisation methodology of introducing inclined conical diffuser in hydraulic turbine. Energy, 265, 126374. https://doi.org/10.1016/j.energy.2022.126374
Zhu, L., Zhang, R., Yu, A., Lu, L., & Luo, X. (2021). Suppression of vortex rope oscillation and pressure vibrations in Francis turbine draft tube using various strategies. Journal of Hydrodynamics, 33(3), 534–545. https://doi.org/10.1007/s42241-021-0038-4
Journal of Applied Fluid Mechanics
Volume 17, Issue 1 - Serial Number 81
January 2024
Pages 219-232

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History

  • Received: 09 May 2023
  • Revised: 07 September 2023
  • Accepted: 12 September 2023
  • Available online: 01 November 2023

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