The structural complexity of hydropower units and the intricate nature of internal flow make it challenging to analyze and resolve abnormal noise issues in hydropower stations. This paper investigates an abnormal noise problem in a specific hydropower unit through a combination of tests and computational fluid dynamics simulations. By analyzing the on-site measured noise spectra, vibration spectra, and pressure fluctuation spectra, potential sources such as draft tube vortex, runner-stator interaction (RSI), inter-blade vortex, and air supply valve vibration were systematically excluded. The abnormal noise source was ultimately identified as resonance triggered by Karman vortex shedding from the turbine runner, based on the analysis of the locked-in phenomenon and the calculation of vortex shedding frequency. After thinning the trailing edges of the runner blades on site, the abnormal noise, along with the associated vibration and pressure fluctuation, was effectively eliminated. Noise and vibration near the runner were significantly reduced under all load conditions, with the maximum noise energy in the turbine chamber reduced by 95.2% and the vibration amplitude at the main frequency in the draft tube reduced to only 2% of its original value. This work provides a method for quickly analyzing and resolving flow-induced abnormal noise issues, offering theoretical and practical support for addressing abnormal noise problems in hydro-turbines.
VagnoniEGezerDAnagnostopoulosI, et al.The new role of sustainable hydropower in flexible energy systems and its technical evolution through innovation and digitalization. Renew Energy2024; 230: 120832. https://doi.org/10.1016/j.renene.2024.120832
2.
WuYLiSLiuS, et al.Vibration of hydraulic machinery. Springer, 2013.
3.
WangWYuZYanY, et al.Numerical investigation on vortex characteristics in a low-head Francis turbine operating of adjustable-speed at part load conditions. Energy2024; 302: 131800. https://doi.org/10.1016/j.energy.2024.131800
4.
AminiAVagnoniEFavrelA, et al.Upper part-load instability in a reduced-scale Francis turbine: an experimental study. Exp Fluids2023; 64(6): 110. https://doi.org/10.1007/s00348-023-03649-0
5.
TangQYuAWangY, et al.Numerical analysis of vorticity transport and energy dissipation of inner-blade vortex in Francis turbine. Renew Energy2023; 203: 634–648. https://doi.org/10.1016/j.renene.2022.12.086
6.
DörflerPSickMCoutuA. Flow-induced pulsation and vibration in hydroelectric machinery: engineer's guidebook for planning, design and troubleshooting. Springer, 2013.
7.
TrivediCCervantesMJ. Fluid-structure interactions in Francis turbines: a perspective review. Renew Sustain Energy Rev2017; 68: 87–101. https://doi.org/10.1016/j.rser.2016.09.121
8.
ChengHZhouLLiangQ, et al.The investigation of runner blade channel vortices in two different Francis turbine models. Renew Energy2020; 156: 201–212. https://doi.org/10.1016/j.renene.2020.04.015
9.
WangHLiWHouY, et al.Recognition of the developing vortex rope in Francis turbine draft tube based on PSO-CS2. Renew Energy2023; 217: 119114. https://doi.org/10.1016/j.renene.2023.119114
KumarSCervantesMJGandhiBK. Rotating vortex rope formation and mitigation in draft tube of hydro turbines – a review from experimental perspective. Renew Sustain Energy Rev2021; 136: 110354. https://doi.org/10.1016/j.rser.2020.110354
12.
ChengHZhouLLiangQ, et al.A method of evaluating the vortex rope strength in draft tube of Francis turbine. Renew Energy2020; 152: 770–780. https://doi.org/10.1016/j.renene.2020.01.020
13.
AlligneSBNicoletCAvellanFO. Identification of Francis turbine helical vortex rope excitation by CFD and resonance simulation with the hydraulic system. ASME, 2011, pp. 481–493. https://doi.org/10.1115/AJK2011-06089
14.
NicoletCArpeJAvellanF. Identification and modeling of pressure fluctuations of a Francis turbine scale model at part load operation, pp. 1–17. International Association For Hydraulic Research, 2004.
15.
AllignéSNicoletCAvellanF. Identification by CFD simulation of the mechanism inducing upper part load resonance phenomenon. Proceedings of the 4th international meeting on cavitation and dynamic problems in hydraulic machinery and systems, Belgrade, Serbia. 2011.
16.
NicoletCZobeiriAMaruzewskiP, et al.Experimental investigations on upper part load vortex rope pressure fluctuations in Francis turbine draft tube. International Journal of Fluid Machinery and Systems2011; 4(1): 179–190. https://doi.org/10.5293/ijfms.2011.4.1.179
17.
FrunzǎverdeDMunteanSMǎrgineanG, et al.Failure analysis of a Francis turbine runner, Iop conference series. Earth and Environmental Science2010; 12(1): 012115. https://doi.org/10.1088/1755-1315/12/1/012115
18.
ZhuDTaoRXiaoR, et al.Solving the runner blade crack problem for a Francis hydro-turbine operating under condition-complexity. Renew Energy2020; 149: 298–320. https://doi.org/10.1016/j.renene.2019.12.057
19.
KCALeeYHThapaB. CFD study on prediction of vortex shedding in draft tube of Francis turbine and vortex control techniques. Renew Energy2016; 86: 1406–1421. https://doi.org/10.1016/j.renene.2015.09.041
20.
WangLCuiJShuL, et al.Research on the vortex rope control techniques in draft tube of Francis turbines. Energies2022; 15(24): 9280. https://doi.org/10.3390/en15249280
21.
LiDYuLYanX, et al.Runner cone optimization to reduce vortex rope-induced pressure fluctuations in a Francis turbine, science China. Technological Sciences2021; 64(9): 1953–1970. https://doi.org/10.1007/s11431-021-1867-2
22.
SunLLiYGuoP, et al.Numerical investigation of air admission influence on the precessing vortex rope in a Francis turbine. Eng Appl Comp Fluid2023; 17(1): 2164619. https://doi.org/10.1080/19942060.2022.2164619
23.
AnupKCThapaBLeeY. Transient numerical analysis of rotor–stator interaction in a Francis turbine. Renew Energy2014; 65: 227–235.
24.
NicoletCRuchonnetNAllignéS, et al.Hydroacoustic simulation of rotor-stator interaction in resonance conditions in Francis pump-turbine, pp. 012005. IOP Publishing, 2010.
25.
LvYWangZZhouL. Study of the phase resonance phenomenon in Francis turbine, Iop conference series. Earth and Environmental Science2022; 1037(1): 12051.
26.
HeLYWangZWKurosawaS, et al.Resonance investigation of pump-turbine during startup process. IOP Publishing, 2014, pp. 032024.
27.
ZhangFLowysPYHoudelineJB, et al.Pump-turbine rotor-stator interaction induced vibration: problem resolution and experience. IOP Conf Ser Earth Environ Sci2021; 774(1): 12124. https://doi.org/10.1088/1755-1315/774/1/012124
LiuDLiuXZhaoY. Experimental investigation of inter-blade vortices in a model Francis turbine. Chin J Mech Eng-En2017; 30(4): 854–865. https://doi.org/10.1007/s10033-017-0097-1
30.
YexiangXZhengweiWZongguoY. Experimental and numerical analysis of blade channel vortices in a Francis turbine runner. Eng Comput2011; 28(2): 154–171. https://doi.org/10.1108/02644401111109204
31.
BouajilaSDe ColombelTLowysP, et al.Hydraulic phenomena frequency signature of Francis turbines operating in part load conditions. IOP Conf Ser: Earth Environ. Sci2016; 49(8): 82001.
32.
LiuSZhangLWuY, et al.Influence of 3D guide vanes on the channel vortices in the runner of a Francis turbine. J Fluid Sci Technol2006; 1(2): 147–156. https://doi.org/10.1299/jfst.1.147
SunLGuoPWuL. Numerical investigation of alleviation of undesirable effect of inter-blade vortex with air admission for a low-head Francis turbine. J Hydrodyn2020; 32: 1151–1164. https://doi.org/10.1007/s42241-020-0081-6
35.
ZanettiGCavazziniGSantolinA. Effect of the von Karman shedding frequency on the hydrodynamics of a Francis turbine operating at nominal load. International Journal of Turbomachinery, Propulsion and Power2023; 8(3): 27. https://doi.org/10.3390/ijtpp8030027
36.
XiaXZhouLWangZ, et al.Effects of trailing-edge modification of guide vanes on the wake vortices under different inflow conditions, proceedings of the institution of mechanical engineers. Part a. Journal of Power and Energy2021; 235(8): 1892–1901. https://doi.org/10.1177/09576509211017434
37.
NennemannBMonetteC. Prediction of vibration amplitudes on hydraulic profiles under von Karman vortex excitation, Iop conference series. Earth and Environmental Science2019; 240(6): 62004.
38.
TitzschkauMDörflerP. Solving the challenging puzzle of the Grimsel II runner vibration, Iop conference series. Earth and Environmental Science2022; 1079(1): 12099.
39.
FisherJHGCRK. Stay vane vibrations in the Nkula Falls turbines. In: International journal on hydropower and dams, Aqua-Media International, 1994.
40.
DolmatovENIlinSYEliferovVV, et al.Air injection as a solution to the problem for reducing high-frequency acoustic noise in some operating modes of Francis hydro turbines. E3S Web of Conferences2021; 320: 4005. https://doi.org/10.1051/e3sconf/202132004005
41.
PengXZhouJZhangC, et al.An intelligent optimization method for vortex-induced vibration reducing and performance improving in a large Francis turbine. Energies2017; 10(11): 1901. https://doi.org/10.3390/en10111901
42.
CelikIGhiaURoachePJ, et al. Procedure for estimation and reporting of uncertainty due to discretization in CFD applications. J Fluid Eng. 2008; 130(7): 078001. https://doi.org/10.1115/1.2960953
