Operating conditions leading to crack propagation in turbine blades of tidal barrages. Influence of head and operating mode

Luo, Yongyao; Presas, Alexandre; Wang, Zhengwei; Xiao, Yexiang; Wang, Haoping; Xiao-yi, Jiang

doi:10.1016/j.engfailanal.2019.104254

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…1. When the crack opens, the surface contact force of the breathing crack in the local coordinate system can be expressed as (Luo et al, 2019)…”

Section: Crack Surface Contact Forcementioning

confidence: 99%

Nonlinear dynamic model of a turbine blade considering vibration and crack coupling

Wang,

Luo,

Huang

et al. 2024

Journal of Theoretical and Applied Mechanics

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In order to further investigate dynamic characteristics of turbine runner blades under the coupling effect of vibration and crack, in this article, a runner blade with a crack was taken as the research object. The coupling effect of vibration and crack was analyzed, a nonlinear dynamic model considering the coupling of the runner blade was developed, and the vibration and fatigue characteristics were investigated. First, based on the contact characteristics of the breathing crack surfaces in the runner blade under hydraulic excitation, a breathing crack surface contact model was established. Subsequently, a nonlinear dynamic model considering the coupling effect of vibration and crack was obtained. The crack surface contact force and crack stiffness matrix were established and the vibration and fatigue characteristics were analyzed. Finally, the feasibility of the dynamic model was verified by a case study, and the dynamic and vibration fatigue characteristics under the coupling effect of vibration and crack were revealed. The research results show that with propagation of the crack, the crack surface contact force increases and the dynamic stress amplitude at the crack tip increases as well. When the sum of the frequency of the hydraulic excitation and the crack surface contact force acting on the runner blade is close to the natural frequency of the runner blade, a combined resonance will occur. When the coupling effect of vibration and crack is taken into consideration, the vibration fatigue crack propagation model is more accurate and can provide a basis for fatigue strength and life prediction of runner blades.

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“…1. When the crack opens, the surface contact force of the breathing crack in the local coordinate system can be expressed as (Luo et al, 2019)…”

Section: Crack Surface Contact Forcementioning

confidence: 99%

Nonlinear dynamic model of a turbine blade considering vibration and crack coupling

Wang,

Luo,

Huang

et al. 2024

Journal of Theoretical and Applied Mechanics

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“…In order to study the overall behavior related to, for instance, global stress/strain levels, tip deflection, and Eigen-Frequencies. The Finite Element Method (FEM) is highly practical and has historically been successfully deployed in the development of tidal turbine blades (Luo et al, 2020). No publications have been conducted previously on finite element (FE) modeling using ABAQUS software to investigate all pertinent behavioral aspects and stability problems of tidal turbines.…”

Section: Numerical Investigationmentioning

confidence: 99%

Modal analysis of composite nozzle for an optimal design of a tidal current turbine

Laaouidi¹,

Tarfaoui

Nachtane³

et al. 2021

J. nav. arch. mar. engg.

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Monitoring of structural vibrations and operational modal analysis are clearly essential to effectively control structural safety and the operational behavior of tidal current turbines. In order to satisfy industrial requirements, generally related to a mass gain problem, hybridization provides an excellent method to improve the breaking strength of composite materials, while keeping adequate mechanical performance for marine renewable energy applications. In this context, this work aims to study the structural modal analysis of a tidal turbine nozzle and the effect of hybrid materials (carbon/Glass) on the natural frequencies and corresponding mode shapes of the three laminates. The modal analysis was calculated by the Finite Element Method using ABAQUS software. According to the results, the stacking sequence has a considerable impact on the natural frequency of the nozzle. Furthermore, it is also found that the resonance effect does not appear for the three laminates under investigation.

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“…For instance, rotating vortex ropes and vanless space vortex structures [1-5] threaten the safe operation of hydraulic turbines. And large relative variations in head [6], free surface vortices or upstream and downstream water level fluctuations [7,8] compromise the operation of marine and runof-river turbines. In order to minimize the risks of these phenomena, it is of paramount importance to determine the modal responses, i.e., the natural frequencies, mode shapes, and damping ratios, of the machines.…”

Section: Introductionmentioning

confidence: 99%

On the Added Modal Coefficients of a Rotating Submerged Cylinder Induced by a Whirling Motion—Part 1: Experimental Investigation

Roig,

Sánchez-Botello,

Jou

et al. 2023

JMSE

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The operation of submerged rotating machines, such as marine current or tidal turbines, can present deleterious fluid phenomena that may provoke extreme structural vibrations. To predict their dynamic responses, it is necessary to know the added modal coefficients of their runners under a whirling motion. For that purpose, a bespoke test rig was designed to investigate the added modal coefficients of a submerged cylinder, which could rotate at different speeds both in air and completely submerged in water inside a cylindrical tank. First, the modes of vibration were experimentally measured by exciting the cylinder with a push-release method during steady tests or with ramps in rotating speed during transient tests. The calculated natural frequencies and damping ratios were then used in a mathematical model of the dynamic system to calculate the added modal coefficients. During steady tests, the natural frequencies and damping ratios of the whirling modes changed significantly as a function of the rotating speed. Additionally, a whirling mode was observed to change its direction at a given rotating speed. During transient tests, rotating speed ramps with high accelerations were found to present lower lock-in amplitude and frequencies. Moreover, fast downward ramps presented lock-in amplitudes four times higher than fast upward ramps. Consequently, the added modal coefficients changed accordingly as a function of the rotating speed, ramp acceleration, and ramp direction. For these reasons, it was confirmed that the modal responses of submerged rotating bodies must be calculated for each operational rotating speed, even at low velocities, and for each transient event in order to precisely predict their vibration behaviors.

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Operating conditions leading to crack propagation in turbine blades of tidal barrages. Influence of head and operating mode

Cited by 8 publications

References 36 publications

Nonlinear dynamic model of a turbine blade considering vibration and crack coupling

Nonlinear dynamic model of a turbine blade considering vibration and crack coupling

Modal analysis of composite nozzle for an optimal design of a tidal current turbine

On the Added Modal Coefficients of a Rotating Submerged Cylinder Induced by a Whirling Motion—Part 1: Experimental Investigation

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