Journal of Fluids and Structures最新文献_第4页

Experimental study of wake-induced vibration response in a flexibly mounted tandem cylinder system with a prescribed dynamically oscillating upstream cylinder

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-27 DOI: 10.1016/j.jfluidstructs.2024.104247

Sarah Dulac, Hamed Samandari, Banafsheh Seyed-Aghazadeh

The wake-induced vibration (WIV) of a flexibly mounted circular cylinder, positioned in tandem with an upstream circular cylinder, is investigated through experimental analysis. The upstream cylinder undergoes forced oscillations with a peak-to-peak amplitude of 0.5 times the cylinder’s diameter (

D

) and frequencies ranging from 0.5 to 2 times the natural frequency of the downstream cylinder. By imposing a prescribed motion on the upstream cylinder, this study diverges from conventional investigations of WIV in tandem cylinder arrangements. In our approach, the downstream cylinder responds to a wake characterized by independently controlled dynamics – such as wake width and shedding frequency – distinct from the geometry and inherent characteristics of the source cylinder. This study examines oscillation amplitudes, frequencies, and flow forces in a reduced velocity range of

U^{*}

= 2.9 – 18.0, corresponding to Reynolds numbers of 650 to 3500, across various center-to-center spacings of

S / D

= 4, 6, 8. Qualitative and quantitative flow field assessments are conducted using hydrogen bubble imaging and a volumetric Particle Tracking Velocimetry (PTV) technique, respectively.

The dynamic response shows that the downstream cylinder experiences WIV for each forcing frequency ratio. Due to the distinct wake dynamics created in each case, the downstream cylinder experiences continuous large-amplitude oscillations persisting to the highest reduced velocity tested at a frequency ratio of 1. At a frequency ratio of 2, the onset of oscillations is delayed to higher reduced velocities. The frequency contents of the observed oscillations directly correspond to the prescribed upstream motion, indicating the detection of the incoming wake. The wake structure developed downstream shows a strong dependence on the dynamic characteristics of the upstream cylinder. A Q-criterion analysis reveals the dominant structures prevailing downstream of the tandem pair and their three-dimensional nature. Additionally, a spatiotemporal mode analysis using the proper orthogonal decomposition technique elucidates the coherent vortical structures responsible for the various downstream cylinder responses observed in each upstream condition.

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引用次数: 0

Theoretical analysis of liquid wave motion in rotating cylinder depending on liquid depth ratio

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-27 DOI: 10.1016/j.jfluidstructs.2024.104250

Fumitaka Yoshizumi

The fluid force caused by the wave motion of liquid that partially fills a hollow rotor was theoretically investigated, with a focus on the motion's relationship with the radial liquid depth. The fluid force causes a self-excited whirl of the rotor. To obtain the excitation force as a function of the liquid depth, a nonlinear analysis method that does not use shallow water approximation is presented. Gravity is negligible and the liquid motion is assumed to be axially uniform. The linear eigenmodes of the two-dimensional flow in the radial and circumferential directions are nonlinearly coupled through the Galerkin method. The periodic solution of the wave response to the whirl motion is obtained and is compared with the conventional shallow water approximation. In the present theory, the excitation force reaches its maximum at a specific liquid depth that is consistent with previous experimental studies, while the maximum does not appear in the shallow water approximation. Furthermore, the present theory indicates that the response of the first eigenmode that causes the excitation force is suppressed by nonlinearity when the liquid is shallow; in contrast, when the liquid is deep, the first eigenmode self-balances with disturbance of the whirl motion without the help of nonlinearity. The decrease in the helping role of nonlinearity in a deep liquid comes from the ratio of the radial flow velocity to the circumferential flow velocity in the eigenfunction becoming large as the liquid depth ratio increases.

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引用次数: 0

Performance and mechanism of the hydrodynamic noise reduction for biomimetic trailing-edge serrations of a submarine

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-24 DOI: 10.1016/j.jfluidstructs.2024.104256

Zhihao Ma , Peng Li , Hang Guo , Kuai Liao , Yiren Yang

As submarine speed increases, the hydrodynamic noise generated by the sail of a submarine becomes more pronounced. Inspired by the noise reduction capabilities demonstrated by the serration on the owl’s wing trailing edge, this paper proposes the serration noise reduction structure applied to the sail trailing edge of the submarine. The large eddy simulation and the Ffowcs Williams–Hawkings equation are employed to examine the impact of serration on flow and noise characteristics at the sail. The quadrupole noise source is captured by the permeable surface combined with the formulation Q1A. The physical mechanisms underlying trailing edge serration, which reduce flow noise, are revealed. The accuracy of the hydrodynamic and acoustic calculation methods is verified by experimental data. This study demonstrates that the serration exerts the double effect on the flow noise, which is a combination of dipole and quadrupole noise. Total noise is reduced by up to 4.32 dB. The impact of serration on dipole noise is the combined behavior of multiple physical mechanisms. First, the serration induces flow separation at the trailing edge and block water convergence at the serration peak, thereby diminishing turbulent fluctuations within the boundary layer; Secondly, it causes the decoherence effect on the vertical pressure fluctuations at the trailing edge, resulting in destructive interference in the dipole noise source. The serrations extend the continuous Stream vortex, delaying its evolution into the Hairpin vortex and subsequent fragmentation into small-scale vortex. This distortion of the spatial vortex structure intensifies the magnitude of the Lamb vector

| ℒ |

and Lighthill stress, thereby enhancing the energy of quadrupole noise source. Flow noise reduction is achieved by applying sail trailing edge serration in a submarine, but the submarine hull diminishes its noise reduction performance. The reason involves turbulent interference in the boundary layer of the hull altering the incoming flow conditions at the trailing edge serration, which increases the unsteady pressure fluctuations at the serration valley, thereby amplifying the intensity of the dipole noise source.

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引用次数: 0

Effect of confinement on the hydrodynamic performance of a fully-passive oscillating-foil turbine

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-24 DOI: 10.1016/j.jfluidstructs.2024.104258

Sierra Mann , Guy Dumas , Peter Oshkai

An experimental study was conducted to assess the effects of flow confinement on the hydrodynamic performance of a fully-passive oscillating-foil turbine at a Reynolds number of 19,000. The experiments were performed using a National Advisory Committee for Aeronautics (NACA) 0015 foil with an aspect ratio of 7.5 in a water tunnel equipped with adjustable lateral walls. The kinematic parameters of the foil oscillations and its energy harvesting performance were measured at eight blockage ratios, ranging from 21 % to 60 %. Quantitative flow imaging was performed using particle image velocimetry (PIV) to observe the timing of the leading-edge vortex (LEV) formation and shedding. Loading on the foil was related to the flow structure by calculating the moments of vorticity with respect to the pitching axis of the foil. The efficiency and the power coefficient increased with increasing confinement and constant upstream velocity. At the highest level of confinement, the proximity of the foil to the walls during parts of the oscillation cycle resulted in a change in the phase lag between the pitching and the heaving components of the foil motion. In turn, this shift in the kinematic parameters led to a sharp decrease in the energy-extraction performance of the turbine.

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引用次数: 0

Vibro-acoustic modeling and energy transmission analysis of a panel-cavity system embedded with an acoustic black hole

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-20 DOI: 10.1016/j.jfluidstructs.2024.104254

Yuhang Wang , Yunchuan Wang , Jinlu Sheng , Jingtao Du , Yang Liu , Zheng Dai , Xiuyi Lyu

The noise radiated from a vibrating panel into an acoustical cavity is a problem widely encountered in various engineering branches. As a novel vibration and noise control means, Acoustic Black Hole (ABH) is attracting more and more research attention, and a deep understanding on the coupling mechanism between ABH panel and cavity is of fundamental significance for the efficient design and application in such occasions. In this study, a semi-analytical vibro-acoustic coupling model of the coupled ABH panel-cavity system consisting of an ABH plate and a rectangular cavity is established, in which the two-dimensional and three-dimensional modified Fourier series are chosen as the admissible functions for the flexural vibration of the ABH plate and the sound pressure distribution function in the acoustical cavity, respectively. Through the Rayleigh-Ritz procedure, the modal characteristics and dynamic behavior of the coupling system are solved. First, the accuracy of the proposed model is validated against those calculated from finite element analysis. Then, through the comparison with its uniform counterpart, the introduction of the ABH structure in the coupled panel-cavity system can reduce the noise inside the enclosure. Furthermore, the energy transmission behavior between the ABH plate and the cavity is investigated via the sound intensity vector distribution over the coupling interface. Meanwhile, the noise reduction mechanism of the coupling system is studied from an energy transmission perspective. Finally, the accuracy of the proposed model was verified by the experiment.

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引用次数: 0

The mechanism of galloping control with a passive modal controller

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-20 DOI: 10.1016/j.jfluidstructs.2024.104249

Fuqing Luo, Zhen Lyu, Chuanqiang Gao, Weiwei Zhang

Passive modal controllers (PMC) are widely used in vibration control. However, the mechanism of PMC in galloping control is still unclear due to the limitation of the present quasi-steady theory. The motivation of this study is to reveal the dynamic mechanism of PMC in galloping control at a low Reynolds number (

R e

) via linear stability analysis (LSA) based on the unsteady aerodynamic model. The reduced-order model (ROM) of unsteady flow is identified using the autoregressive with exogenous input (ARX) technique based on the Navier–Stokes equations. Direct numerical simulations are utilized to support relevant results. It is found that the PMC transforms the unstable structural mode into the stable one due to the modal coupling effect. That is the reason for suppressing significant galloping vibration and eliminating the frequency lock-in phenomenon. The results obtained from dynamic mode decomposition (DMD) indicate that the PMC does not directly affect the unsteady vortex shedding, but changes the coupling mode and stability characteristics of the original coupled system. Thus, the second dominant mode of the flow field which is referred to as galloping mode is replaced with the second harmonic vortex shedding mode. Finally, a parametric study is conducted on the galloping control with a PMC from the perspective of system stability. The ROM-based LSA can provide the effective parameter range for PMC design.

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引用次数: 0

Performance study of Coriolis mass flowmeter for hydrogen two-phase flow measurement

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-20 DOI: 10.1016/j.jfluidstructs.2024.104257

Xiangxiang Pei , Xiaobin Zhang

To enhance the performance of Coriolis mass flowmeters (CMFs) in liquid hydrogen-gas hydrogen (LH₂-GH₂) two-phase flow, we developed a theoretical framework that integrates models of decoupling, finite sound speed, Castiglione's second law, and forced vibration response. This framework was implemented numerically in MATLAB to analyze key parameters, including tube vibration amplitude, measurement error, system quality factor, and the energy dissipation ratio due to tube oscillation and two-phase flow. We first validated the effectiveness of the calculation framework in predicting structural frequencies and displacements using ANSYS. The validated framework was then employed to solve and compare the performance of CMFs under LH₂-GH₂ and water-air conditions across a range of temperatures, emphasizing the challenges posed by the low viscosity, low density, and high compressibility of LH₂. Finally, we investigated the effects of driving force amplitude, tube wall thickness, and tube diameter, proposing strategies to optimize CMF functionality under LH₂-GH₂ conditions. This research addresses gaps in understanding the impact of LH₂-GH₂ on CMF performance and introduces a damping model applicable to tubes of arbitrary shape under two-phase flow. Our findings highlight the unique characteristics of CMF operation in LH₂-GH₂ and lay the groundwork for future technical advancements in this area.

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引用次数: 0

Uncertainty quantification and sensitivity analysis of the SST turbulence model applied to VIV

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-18 DOI: 10.1016/j.jfluidstructs.2024.104225

Simone Martini , Mitja Morgut , Riccardo Pigazzini , Lucia Parussini

This paper presents the results of an Uncertainty Quantification and Sensitivity Analysis carried out for the

k - ω

SST turbulence model applied to the bi-dimensional study of Vortex Induced Vibrations of an elastically mounted cylinder. The turbulence model parameters are treated as epistemic uncertain variables and the forward propagation of uncertainty is evaluated using stochastic expansions based on non-intrusive polynomial chaos. The relative contribution of the closure coefficients to the total uncertainty of the output quantities of interest, the non-dimensional amplitude and the frequency ratio, is evaluated using the Sobol indices. The analysis is repeated for different orders of the polynomial chaos expansion. A set of significant coefficients, which contribute most to the uncertainty for this specific case is identified, and furthermore compared with the sets provided for some other selected flow problems in order to gain further insight on the

k - ω

SST turbulence model.

{"title":"Uncertainty quantification and sensitivity analysis of the SST turbulence model applied to VIV","authors":"Simone Martini , Mitja Morgut , Riccardo Pigazzini , Lucia Parussini","doi":"10.1016/j.jfluidstructs.2024.104225","DOIUrl":"10.1016/j.jfluidstructs.2024.104225","url":null,"abstract":"<div><div>This paper presents the results of an Uncertainty Quantification and Sensitivity Analysis carried out for the <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> SST turbulence model applied to the bi-dimensional study of Vortex Induced Vibrations of an elastically mounted cylinder. The turbulence model parameters are treated as epistemic uncertain variables and the forward propagation of uncertainty is evaluated using stochastic expansions based on non-intrusive polynomial chaos. The relative contribution of the closure coefficients to the total uncertainty of the output quantities of interest, the non-dimensional amplitude and the frequency ratio, is evaluated using the Sobol indices. The analysis is repeated for different orders of the polynomial chaos expansion. A set of significant coefficients, which contribute most to the uncertainty for this specific case is identified, and furthermore compared with the sets provided for some other selected flow problems in order to gain further insight on the <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> SST turbulence model.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104225"},"PeriodicalIF":3.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical investigations on wake transition of a 2-DOF elastically mounted circular cylinder

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-18 DOI: 10.1016/j.jfluidstructs.2024.104252

Shristi Singh, Shaligram Tiwari

Present is a three-dimensional (3D) numerical study on vortex-induced vibration (VIV) of an elastically mounted rigid circular cylinder in cross-flow. The cylinder motion has two degrees-of-freedom (2-DOFs), i.e. it can oscillate in both streamwise as well as in transverse directions. The open-source software, ‘OpenFOAM-7′ (Open Field Operation and Manipulation), has been used to solve the governing equations of fluid and cylinder motion. Computations are carried out to investigate the behavior of wake transition from two-dimension to three-dimension (2D to 3D) and the associated flow characteristics over range of values of reduced velocity (U_r), Reynolds number (Re) and mass ratio (m*). In particular, the range of U_r (2 ≤ U_r ≤ 10) encompasses both lock-in and non-lock-in regimes, where lock-in refers to synchronous oscillations of the cylinder and the wake. Effect of U_r on unsteady wake has been examined using vorticity contours and iso-Q surfaces. The temporal behavior of both the cylinder and wake oscillations has been analyzed using Hilbert spectra. The critical value of Re (

R e_{c r}

) for transition from 2D to 3D through ‘mode C’ type of instability is ascertained for fixed values of m* and U_r. Thereafter, the critical values of m* and Re are obtained by considering their mutual variation for fixed U_r and the associated mode transition is identified. At small values of m*, ‘mode C’ type of instability appears which changes to ‘mode A’ type for larger m*.

{"title":"Numerical investigations on wake transition of a 2-DOF elastically mounted circular cylinder","authors":"Shristi Singh, Shaligram Tiwari","doi":"10.1016/j.jfluidstructs.2024.104252","DOIUrl":"10.1016/j.jfluidstructs.2024.104252","url":null,"abstract":"<div><div>Present is a three-dimensional (3<em>D</em>) numerical study on vortex-induced vibration (VIV) of an elastically mounted rigid circular cylinder in cross-flow. The cylinder motion has two degrees-of-freedom (2-DOFs), i.e. it can oscillate in both streamwise as well as in transverse directions. The open-source software, ‘OpenFOAM-7′ (Open Field Operation and Manipulation), has been used to solve the governing equations of fluid and cylinder motion. Computations are carried out to investigate the behavior of wake transition from two-dimension to three-dimension (2<em>D</em> to 3<em>D</em>) and the associated flow characteristics over range of values of reduced velocity (<em>U<sub>r</sub></em>), Reynolds number (<em>Re</em>) and mass ratio (<em>m*</em>). In particular, the range of <em>U<sub>r</sub></em> (2 ≤ <em>U<sub>r</sub></em> ≤ 10) encompasses both lock-in and non-lock-in regimes, where lock-in refers to synchronous oscillations of the cylinder and the wake. Effect of <em>U<sub>r</sub></em> on unsteady wake has been examined using vorticity contours and iso-Q surfaces. The temporal behavior of both the cylinder and wake oscillations has been analyzed using Hilbert spectra. The critical value of <em>Re</em> (<span><math><mrow><mi>R</mi><msub><mi>e</mi><mrow><mi>c</mi><mi>r</mi></mrow></msub></mrow></math></span>) for transition from 2<em>D</em> to 3<em>D</em> through ‘mode C’ type of instability is ascertained for fixed values of <em>m*</em> and <em>U<sub>r</sub></em>. Thereafter, the critical values of <em>m*</em> and <em>Re</em> are obtained by considering their mutual variation for fixed <em>U<sub>r</sub></em> and the associated mode transition is identified. At small values of <em>m*</em>, ‘mode C’ type of instability appears which changes to ‘mode A’ type for larger <em>m*</em>.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104252"},"PeriodicalIF":3.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An unsteady aerodynamic reduced-order modelling framework for shock-dominated flow with application on shock-induced panel flutter prediction

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-16 DOI: 10.1016/j.jfluidstructs.2024.104251

Hao Zhou , Mingyv Nie , Mengzhu Qin , Gang Wang

A fully data-driven unsteady aerodynamic reduced-order modelling framework based on the nonlinear autoregressive with exogenous input structure is established for fluid-structure coupling simulations in the shock dominated flow. A generalized radial basis function neural network extended with polynomials is used for mapping the regressors and model outputs. The training with validation techniques is adopted to enhance the model's generalization ability, and the Bayesian optimization algorithm is selected for hyperparameter tunning. In addition, the fluid-structure coupling is incorporated into the validation process with a modified loss function to improve the robustness of the trained models. Both a generalized aerodynamic force model and a proper orthogonal decomposition based distributed aerodynamic force model are constructed and tested for the prescribed surface motions and fluid-structure coupling simulations. The results show that the constructed models have high accuracy in the forced oscillation tests, and the predicted amplitudes and frequencies of limit cycle oscillations in the shock-induced panel flutter are in excellent agreement with computational fluid dynamics/computational structural dynamics coupling simulations. The statistical results show that the online computational cost of the reduced-order model are orders of magnitude less than that required for the computational fluid dynamics method, indicating the presented modelling framework is an effective tool for the shock dominated aeroelastic problem analysis.

{"title":"An unsteady aerodynamic reduced-order modelling framework for shock-dominated flow with application on shock-induced panel flutter prediction","authors":"Hao Zhou , Mingyv Nie , Mengzhu Qin , Gang Wang","doi":"10.1016/j.jfluidstructs.2024.104251","DOIUrl":"10.1016/j.jfluidstructs.2024.104251","url":null,"abstract":"<div><div>A fully data-driven unsteady aerodynamic reduced-order modelling framework based on the nonlinear autoregressive with exogenous input structure is established for fluid-structure coupling simulations in the shock dominated flow. A generalized radial basis function neural network extended with polynomials is used for mapping the regressors and model outputs. The training with validation techniques is adopted to enhance the model's generalization ability, and the Bayesian optimization algorithm is selected for hyperparameter tunning. In addition, the fluid-structure coupling is incorporated into the validation process with a modified loss function to improve the robustness of the trained models. Both a generalized aerodynamic force model and a proper orthogonal decomposition based distributed aerodynamic force model are constructed and tested for the prescribed surface motions and fluid-structure coupling simulations. The results show that the constructed models have high accuracy in the forced oscillation tests, and the predicted amplitudes and frequencies of limit cycle oscillations in the shock-induced panel flutter are in excellent agreement with computational fluid dynamics/computational structural dynamics coupling simulations. The statistical results show that the online computational cost of the reduced-order model are orders of magnitude less than that required for the computational fluid dynamics method, indicating the presented modelling framework is an effective tool for the shock dominated aeroelastic problem analysis.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104251"},"PeriodicalIF":3.4,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0