Understanding the Influence of Wake Cavitation on the Dynamic Response of Hydraulic Profiles under Lock-In Conditions

Roig, Rafel; Chen, Jian; Torre, Oscar de la; Escaler, Xavier

doi:10.3390/en14196033

Cited by 7 publications

(2 citation statements)

References 26 publications

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“…Based on this phenomenon, the theoretical basis for the stability of this vortex was proposed by Von Karman from the view of aerodynamics. Therefore, this type of vortex is also called a Karman vortex in the theoretical study of fluid mechanics [6,7]. When the Karman vortex appears, the water flow will generate a periodic transverse alternating force on the object.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Fractal Characteristics of Karman Vortex for NACA0009 Hydrofoil

et al. 2023

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A Karman vortex is a phenomenon of fluid flow that can cause fluctuation and vibration. As a result, it leads to fatigue damage to structures and induces safety accidents. Therefore, the analysis of the shedding law and strength of the Karman vortex is significant. To further understand the laws of turbulent Karman vortex shedding and strength, this study conducts a numerical vorticity simulation of a Karman vortex at the trailing edge of a hydrofoil based on the two-dimensional simplified model of the NACA0009 hydrofoil under different Reynolds numbers. Combined with image segmentation technology, the fractal characteristics of a turbulent Karman vortex at the trailing edge of a hydrofoil are extracted, the number and total area of vortex cores are calculated, and the fractal dimension of the vortex is obtained. The results show that the fractal dimension can characterize the change in vortex shape and strength under different Reynolds numbers, and that the fractal analysis method is feasible and effective for the shedding analysis of a turbulent Karman vortex.

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Section: Introductionmentioning

confidence: 99%

Investigation of Fractal Characteristics of Karman Vortex for NACA0009 Hydrofoil

et al. 2023

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“…The natural frequency and added mass were calculated using an acoustic-structural modal analysis prior to performing: (i) a URANS simulation to calculate the added damping, and (ii) a Reynolds-Averaged Navier-Stokes (RANS) simulation to calculate the added stiffness. Roig et al [11] used a similar numerical methodology to investigate the influence of the wake cavitation on the dynamic response of hydraulic profiles under lock-in conditions. The numerical results correlated well with the corresponding experimental results, which also validated the methodology.…”

Section: Introductionmentioning

confidence: 99%

On the Added Modal Coefficients of a Rotating Submerged Cylinder Induced by a Whirling Motion—Part 2: Numerical Investigation

Roig,

Sánchez-Botello,

Escaler

2023

JMSE

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Part 2 of this work presents a numerical methodology, validated using the experimental results presented in Part 1, to calculate the added modal coefficients of a submerged cylinder in water both when it oscillates and when it rotates with a whirling motion. The numerical methodology is based on computational fluid dynamic simulations that obtain the added modal forces on the cylinder when it is forced to vibrate with mode shapes calculated using acoustic-structural modal analysis. Then, these forces are processed with a curve-fitting algorithm to extract all the coefficients. Most numerical coefficients presented a close agreement with the corresponding experimental ones, although the added modal damping was overestimated. In general, the added modal mass was found to be independent of both the rotating speed and the whirling frequency except for low whirling frequencies when it increased. The added modal damping was found to depend on both parameters, and the rest of the coefficients were independent of the whirling frequency and only depended on the rotating speed. As a conclusion, this numerical approach has permitted the study of particular conditions that could not be experimentally tested and thus broadened the knowledge of the behavior of the added modal coefficients of rotating submerged cylinders.

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A Review of the Hydrodynamic Damping Characteristics of Blade-like Structures: Focus on the Quantitative Identification Methods and Key Influencing Parameters

Zeng,

Qian,

Zhang

et al. 2024

J. Marine. Sci. Appl.

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Abstractcean energy has progressively gained considerable interest due to its sufficient potential to meet the world’s energy demand, and the blade is the core component in electricity generation from the ocean current. However, the widened hydraulic excitation frequency may satisfy the blade resonance due to the time variation in the velocity and angle of attack of the ocean current, even resulting in blade fatigue and destructively interfering with grid stability. A key parameter that determines the resonance amplitude of the blade is the hydrodynamic damping ratio (HDR). However, HDR is difficult to obtain due to the complex fluid–structure interaction (FSI). Therefore, a literature review was conducted on the hydrodynamic damping characteristics of blade-like structures. The experimental and simulation methods used to identify and obtain the HDR quantitatively were described, placing emphasis on the experimental processes and simulation setups. Moreover, the accuracy and efficiency of different simulation methods were compared, and the modal work approach was recommended. The effects of key typical parameters, including flow velocity, angle of attack, gap, rotational speed, and cavitation, on the HDR were then summarized, and the suggestions on operating conditions were presented from the perspective of increasing the HDR. Subsequently, considering multiple flow parameters, several theoretical derivations and semi-empirical prediction formulas for HDR were introduced, and the accuracy and application were discussed. Based on the shortcomings of the existing research, the direction of future research was finally determined. The current work offers a clear understanding of the HDR of blade-like structures, which could improve the evaluation accuracy of flow-induced vibration in the design stage.

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Understanding the Influence of Wake Cavitation on the Dynamic Response of Hydraulic Profiles under Lock-In Conditions

Cited by 7 publications

References 26 publications

Investigation of Fractal Characteristics of Karman Vortex for NACA0009 Hydrofoil

Investigation of Fractal Characteristics of Karman Vortex for NACA0009 Hydrofoil

On the Added Modal Coefficients of a Rotating Submerged Cylinder Induced by a Whirling Motion—Part 2: Numerical Investigation

A Review of the Hydrodynamic Damping Characteristics of Blade-like Structures: Focus on the Quantitative Identification Methods and Key Influencing Parameters

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