Journal of Fluids and Structures最新文献_第6页

Impact loads and ice plate damage during the process of icebreaking and water exit for the vehicle 车辆破冰出水过程中的冲击载荷和冰板损伤

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-09 DOI: 10.1016/j.jfluidstructs.2025.104463

Zhiqiang Fu , Zhipeng Li , Longquan Sun , Guihui Ma , Siqiang Wang

Underwater vehicles in polar environments invariably encounter complex operating conditions, including interactions with ice and water. The substantial impact loads and hydrodynamic forces generated by the interaction among the vehicle structure, ice, and water during the processes of icebreaking and crossing the water can significantly affect the safety of the vehicle. Therefore, the processes of ice plate breakup, fluid flow characteristics, and the associated complex load dynamics during the icebreaking operations warrant thorough investigation. In response to this need, this paper presents a set of experimental systems designed to study vehicle icebreaking and water-exit. A type of breakable frozen model ice is used in the experiment, and research is conducted on icebreaking loads and the breakup of ice plates when vehicles impact ice plates of varying thicknesses and sizes at different speeds. The results of experiments indicate that radial cracks develop first, followed by the propagation of circumferential cracks. The study reveals that, due to the obstruction posed by the ice plate, an instantaneous pressure peak occurs at the vehicle's bow as it contacts the ice. This pressure is released once the ice sheet breaks, resulting in a splash. Furthermore, as the ice plate length increases, fluctuations in the pressure peak at the vehicle bow are noted. Concurrently, the axial force exhibits an overall upward trend as the size of the ice sheet increases. The findings of this study can serve as a valuable reference for the comprehensive design of marine structures intended for polar operations.

水下航行器在极地环境中总是遇到复杂的操作条件，包括与冰和水的相互作用。在破冰和渡水过程中，车辆结构与冰、水相互作用产生的巨大冲击载荷和水动力会对车辆的安全性产生重大影响。因此，在破冰作业中，冰板破碎过程、流体流动特性以及相关的复杂载荷动力学需要深入研究。针对这一需求，本文设计了一套研究车辆破冰出水的实验系统。实验采用一种可破冰冰冻模型冰，研究车辆以不同速度撞击不同厚度和尺寸的冰板时的破冰载荷和冰板破碎情况。试验结果表明，径向裂纹首先形成，其次是周向裂纹的扩展。研究表明，由于冰板的阻碍，当车辆接触冰时，车辆的船头会出现瞬时压力峰值。一旦冰盖破裂，这种压力就会释放，导致水花飞溅。此外，随着冰板长度的增加，可以注意到车辆艏压力峰值的波动。同时，轴向力随冰盖尺寸的增大总体呈上升趋势。本研究结果可为极地作业海洋结构的综合设计提供有价值的参考。

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引用次数: 0

Aeroelastic response of an airfoil with structural freeplay in transonic buffeting flow 跨声速抖振流中具有结构自由的翼型气动弹性响应

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-08 DOI: 10.1016/j.jfluidstructs.2025.104445

Michael Candon , Vincenzo Muscarello , Wim Verhagen , Pier Marzocca , Oleg Levinski

Transonic shock buffet is a nonlinear, unsteady aerodynamic phenomenon characterized by self-sustained, periodic shock oscillations that can critically affect aircraft structural integrity. While the aerodynamic aspects of shock buffet have been widely studied, its interaction with nonlinear structural dynamics remains largely unexplored. This paper presents, for the first time, a numerical investigation of aeroelastic interactions arising from the coupling of shock buffet with a nonlinear structural model featuring pitch freeplay. Using Unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations coupled with a two-degree-of-freedom heave–pitch airfoil model, the study reveals that structural nonlinearity can induce aerodynamic lock-in to superharmonics of the heave natural frequency, resulting in 2:1 and 3:1 lock-in mechanisms and large-amplitude heave limit cycles. These newly identified lock-in behaviors expand the current understanding of transonic aeroelastic instabilities. The influence of key parameters such as structural-to-fluid mass ratio and structural damping on these phenomena is also systematically examined. This work introduces a novel class of aeroelastic lock-in mechanism with significant implications for transonic flight dynamics and aircraft design.

跨声速冲击是一种非线性、非定常的气动现象，其特征是自我持续的周期性冲击振荡，可以严重影响飞机结构的完整性。虽然冲击冲击的气动方面已经得到了广泛的研究，但它与非线性结构动力学的相互作用在很大程度上仍然是未知的。本文首次用数值方法研究了振动冲击与具有俯距自由运动的非线性结构模型之间的气动弹性相互作用。利用非定常雷诺数-平均纳维-斯托克斯（URANS）模拟和二自由度重-俯仰翼型模型，研究表明，结构非线性会导致升沉固有频率超谐波的气动锁定，导致2:1和3:1的锁定机制和大振幅的升沉极限环。这些新发现的锁定行为扩展了目前对跨音速气动弹性不稳定性的理解。系统地研究了结构与流体质量比和结构阻尼等关键参数对这些现象的影响。这项工作介绍了一类新的气动弹性锁定机构，对跨音速飞行动力学和飞机设计具有重要意义。

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引用次数: 0

Experimental investigation of flexible trailing edge effects on airfoil turbulent-boundary-layer noise 柔性尾缘对翼型湍流边界层噪声影响的实验研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-08 DOI: 10.1016/j.jfluidstructs.2025.104467

Qian Liu , Reza Maryami , Lin Li , Yu Liu

The acoustic characteristics of the NACA 0012 airfoil with a flexible trailing edge (TE) are experimentally investigated. Measurements are conducted at chord-based Reynolds numbers ranging from

1.93 \times 1 0^{5}

and

1.16 \times 1 0^{6}

, with the airfoil set at a zero angle of attack. Flexible TEs made of polyethylene terephthalate, polypropylene, and polyvinyl chloride strips are employed to assess their impact on noise reduction. To elucidate the effect of TE deformation on acoustic performance, the out-of-plane deformation is recorded using high-speed cameras and analyzed with a digital image correlation algorithm. The acoustic results demonstrate that flexible TEs reduce noise by 1–3 dB within the mid-frequency range, with its upper limit shifting to higher frequencies as the free-stream velocity increases, following a scaling law of

f \sim U^{1.5}

. However, noticeable tonal noise persists across various free-stream velocities, with its frequency remaining relatively consistent. Deformation analysis shows that the vibration of the flexible strip plays a key role in generating vortex shedding, which in turn leads to tonal noise. This is further supported by proper orthogonal decomposition (POD) analysis, which indicates that bending deformation, especially near the tip of the strip, is the primary mechanism driving vortex shedding. This bending deformation, associated with lower-order POD modes, generates large-scale flow structures that propagate acoustic waves to the far field, thereby contributing to the observed tonal noise.

对NACA 0012柔性后缘翼型的声学特性进行了实验研究。测量是在弦为基础的雷诺数范围从1.93×105和1.16×106进行，与翼型设置在零迎角。采用聚对苯二甲酸乙二醇酯、聚丙烯和聚氯乙烯条制成的柔性TEs来评估它们对降低噪音的影响。为了阐明TE变形对声学性能的影响，利用高速摄像机记录了TE变形的面外变形，并用数字图像相关算法进行了分析。声学结果表明，柔性TEs在中频范围内降低了1-3 dB的噪声，随着自由流速度的增加，其上限向更高的频率移动，遵循f ~ U1.5的比例定律。然而，在不同的自由流速度下，明显的音调噪声仍然存在，其频率保持相对一致。变形分析表明，柔性带材的振动是产生涡旋脱落的主要原因，而涡旋脱落又导致了调性噪声的产生。适当的正交分解（POD）分析进一步支持了这一点，表明弯曲变形，特别是在带钢尖端附近的弯曲变形，是驱动旋涡脱落的主要机制。这种弯曲变形与低阶POD模式相关联，产生大规模的流动结构，将声波传播到远场，从而导致观察到的音调噪声。

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引用次数: 0

Experimental study on ice breaking by flexural-gravity waves induced by a moving submerged spheroid 水下运动球体诱导弯曲重力波破冰的实验研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-08 DOI: 10.1016/j.jfluidstructs.2025.104451

Hao Tan , Linhua Sun , Baoyu Ni , Shan Wang , Hua-Dong Yao , C. Guedes Soares

A prolate spheroid model is towed beneath an ice sheet in outdoor ice-tank experiments to study the effects of a moving pressure source, which can induce flexural-gravity waves in an ice sheet. To replace the previous cable-driven system, a new underwater towing setup is developed, constraining both the spheroid's horizontal and vertical motions. For the first time, the hydrodynamic forces acting on the body beneath the ice sheet can be directly measured using this setup. Results demonstrate that the spheroid velocity, submergence depth, and ice thickness jointly govern the maximum ice deflection, damage severity, and the drag and lift characteristics of the spheroid. The drag and lift coefficients vary non-monotonically with the velocity, exhibiting distinct differences from the spheroid moving beneath a free surface or a rigid wall. A new dimensionless parameter is proposed to improve the existing ice failure criteria. This new criterion is based on measured ice deflection and a characteristic length scale of the ice sheet, providing a practical and robust parameter for wave-induced ice failure.

在室外冰槽实验中，研究了移动压力源对冰盖弯曲重力波的影响。为了取代以前的缆索驱动系统，开发了一种新的水下拖曳装置，既限制了球体的水平运动，也限制了球体的垂直运动。这是第一次，用这种装置可以直接测量作用在冰盖下身体上的水动力。结果表明，球体速度、淹没深度和冰厚共同决定了球体的最大冰挠度、损伤程度以及阻力和升力特性。阻力和升力系数随速度非单调变化，与在自由表面或刚性壁面下运动的球体表现出明显的不同。提出了一种新的无量纲参数来改进现有的冰破坏准则。该准则基于实测冰的挠度和冰盖的特征长度尺度，为波浪引起的冰破坏提供了一个实用且可靠的参数。

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引用次数: 0

Evaluation of calculation methods for time-averaged hydrodynamic forces on tandem flapping flexible plates: Velocity–pressure integration versus vorticity-based formulations 串联扑动柔性板上时间平均水动力计算方法的评价：速度-压力积分与基于涡度的公式

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-06 DOI: 10.1016/j.jfluidstructs.2025.104450

Dehan Yuan , LinLin Kang , Weicheng Cui , Dixia Fan

This study examines the relationship between the complex wake of tandem flexible plates and the time-averaged force, while comparing the strengths and limitations of two time-averaged force theories. Expressions for the time-averaged force are derived at both the velocity–pressure and vortical levels and analyzed in comparison. The findings indicate no direct correlation between the wake velocity profile and the time-averaged force. Accurate force predictions require both velocity and pressure information from the wake. The vortical-level theory, which omits pressure information, offers practical advantages in experimental fluid mechanics by linking fluid structures to time-averaged forces. In contrast, the velocity–pressure perturbation theory enables force predictions using near-field velocity data. A systematic comparison of the two theories is provided, with recommendations for the decomposition of the physical mechanisms of time-averaged forces in flow field diagnostics and the selection of appropriate control volumes.

本文探讨了柔性板复合尾迹与时均力之间的关系，并比较了两种时均力理论的优缺点。推导了速度-压力和垂直水平下的时间平均力表达式，并进行了比较分析。研究结果表明，尾迹速度剖面与时间平均力之间没有直接关系。准确的力预测需要来自尾流的速度和压力信息。涡流水平理论忽略了压力信息，通过将流体结构与时间平均力联系起来，为实验流体力学提供了实用的优势。相比之下，速度-压力摄动理论可以使用近场速度数据来预测力。对这两种理论进行了系统的比较，并对流场诊断中时间平均力的物理机制分解和适当控制体积的选择提出了建议。

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引用次数: 0

Energy harvesting from vortex-induced vibrations using a pendulum 利用钟摆从涡激振动中收集能量

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-06 DOI: 10.1016/j.jfluidstructs.2025.104449

F.J. Huera-Huarte

This paper presents an experimental investigation into energy harvesting from vortex-induced vibrations (VIV) using a pendulum-based arrangement. A series of experiments were conducted in a water channel to examine the effects of flow velocity and applied braking torque on the pendulum shaft. The motion of the pendulum and the fluid loading were measured and analyzed to assess the power output and dynamic response of the system under varying flow and braking conditions. Results indicate that energy extraction is maximized within a narrow range of flow velocities that induce lock-in response, particularly for the highest braking torques that allow motion on the system. A constant (limited) braking torque was applied to evaluate mechanical power at the shaft, and while the braking function was not optimized, the study demonstrates that the system can achieve energy conversion efficiencies comparable to other VIV-based energy harvesting configurations.

本文介绍了一种利用摆结构收集涡激振动能量的实验研究。在水道中进行了一系列试验，考察了流速和制动扭矩对摆轴的影响。通过测量和分析摆的运动和流体载荷，评估系统在不同流量和制动条件下的功率输出和动态响应。结果表明，在引起锁定响应的狭窄流速范围内，能量提取是最大的，特别是对于允许系统运动的最高制动扭矩。采用恒定（有限）制动扭矩来评估轴处的机械功率，虽然制动功能没有优化，但研究表明，该系统可以实现与其他基于viv的能量收集配置相当的能量转换效率。

引用次数: 0

Machine learning based sensing of particle shape and size using passive artificial cilia 基于机器学习的被动人工纤毛粒子形状和大小感知

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-05 DOI: 10.1016/j.jfluidstructs.2025.104446

Divyaprakash, Amitabh Bhattacharya

Passive biological cilia function as sensory organelles in various animal cells and microorganisms. In this computational study, we demonstrate that tip and base perturbations in an array of flexible passive artificial cilia may be used to detect the size and aspect ratio of ellipse-shaped particles immersed in an oscillatory Couette flow setup. Two-dimensional numerical simulations of the system are carried out for varying particle shape and size, and the immersed boundary method is used to couple the fluid and structure solvers. Kirchhoff rod theory and finite element method are used to evolve the elastic forces in cilia and particle, respectively. A machine learning model, comprising a Long Short-Term Memory (LSTM) network coupled with a regression layer, is trained using the generated data, in which features such as cilia tip deflection and base angle at three time instances are used to sense the particle size and shape. Using unseen simulation data, we show that the trained model is capable of predicting the size and aspect ratio of the particle within an average prediction error of 6 percent over the entire dataset. The model using cilia base deflection appears to be less sensitive to particle aspect ratio compared to the model using cilia tip deflection, especially for smaller particles. This non-optical sensing technique is especially useful for detecting particle size and shape in opaque liquids.

被动生物纤毛是多种动物细胞和微生物的感觉细胞器。在这项计算研究中，我们证明了柔性被动人工纤毛阵列中的尖端和基部扰动可以用来检测浸入振荡库埃特流装置中的椭圆形状颗粒的大小和长径比。对不同颗粒形状和大小的系统进行了二维数值模拟，并采用浸入边界法对流体和结构求解器进行了耦合。采用Kirchhoff杆理论和有限元法分别对纤毛和颗粒的弹性力进行了演化。使用生成的数据训练由长短期记忆（LSTM）网络和回归层组成的机器学习模型，其中使用三个时间实例的纤毛尖端偏转和底角等特征来感知颗粒大小和形状。使用未见过的模拟数据，我们表明训练模型能够在整个数据集的平均预测误差为6%的范围内预测粒子的大小和纵横比。与使用纤毛尖端偏转的模型相比，使用纤毛基部偏转的模型对颗粒宽高比的敏感性较低，特别是对于较小的颗粒。这种非光学传感技术对于检测不透明液体中的颗粒大小和形状特别有用。

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引用次数: 0

Multiphysics analysis of a flexible oscillating water column wave energy converter with dielectric elastomer membrane 介电弹性体膜柔性振荡水柱波能转换器的多物理场分析

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-03 DOI: 10.1016/j.jfluidstructs.2025.104447

Yang Huang , Qing Xiao , Liu Yang , Saishuai Dai , Saeid Lotfian , Feargal Brennan

Flexible wave energy converters (FlexWECs) have emerged as a promising solution to address the limitations of conventional rigid devices in harsh marine environments. Among them, oscillating water column (OWC) systems integrated with dielectric elastomer generators (DEGs) offer simplified architectures, enhanced adaptability, and direct wave-to-electric energy conversion. However, the complex multiphysics interactions between fluid, structure, and electric fields remain poorly understood, hindering design optimization and performance prediction. This study develops a high-fidelity computational framework to simulate the coupled fluid-structure-electric behaviour of a flexible OWC wave energy converter (WEC) with a DEG membrane. The framework is first validated against experimental data, demonstrating good agreement in capturing the deformation of the flexible membrane induced by the coupled electrostatic and hydrodynamic forces. Subsequently, the model is applied to investigate how electric field influences the WEC system behaviour under regular wave excitation. Results show that applying an electric field reduces the effective stiffness of the membrane, leading to increased deformation. Additionally, it does raise overall structural stress levels, especially near the membrane centre and edge regions, where the maximum stresses are observed. Notably, electric excitation induces a secondary deformation mode in the membrane during the near-flat phase. These effects become more pronounced with increasing initial voltage, which also leads to an approximately quadratic increase in output power. The insights gained from this study provide a deeper understanding of fluid-structure-electricity (FSE) interactions in flexible OWC WECs and offer design guidance for enhancing energy harvesting efficiency in next-generation WEC devices.

柔性波浪能转换器（FlexWECs）已成为解决传统刚性设备在恶劣海洋环境中的局限性的一种有前途的解决方案。其中，与介电弹性体发生器（DEGs）集成的振荡水柱（OWC）系统简化了结构，增强了适应性，并实现了直接的波电转换。然而，流体、结构和电场之间复杂的多物理场相互作用仍然知之甚少，这阻碍了设计优化和性能预测。本研究开发了一个高保真的计算框架来模拟带有DEG膜的柔性OWC波能转换器（WEC）的流-固-电耦合行为。该框架首先与实验数据进行了验证，证明了在捕捉由静电和水动力耦合引起的柔性膜变形方面的良好一致性。随后，应用该模型研究了电场在规则波激励下对WEC系统行为的影响。结果表明，施加电场降低了膜的有效刚度，导致变形增加。此外，它确实提高了整体结构应力水平，特别是在膜中心和边缘区域附近，在那里观察到最大应力。值得注意的是，在近平坦阶段，电激励在膜中诱导了二次变形模式。随着初始电压的增加，这些影响变得更加明显，这也导致输出功率大约二次增长。从这项研究中获得的见解提供了对柔性OWC WECs中流体-结构-电（FSE）相互作用的更深入理解，并为提高下一代WEC设备的能量收集效率提供了设计指导。

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引用次数: 0

Numerical simulation of ship hydroelastic responses in 3D realistic ocean waves with occurrence of freak waves 异形波发生时三维现实海浪中船舶水弹性响应的数值模拟

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-11-03 DOI: 10.1016/j.jfluidstructs.2025.104448

Jialong Jiao , Zhenwei Chen , Yuanming Chen , Shuai Chen , Caixia Jiang

Oceangoing ships may encounter rarely occurring waves like freak waves during their operational lifespan, which largely affects the safety of ships. In this paper a two-way CFD-FEM fluid-structure coupled method is adopted to simulate ship motions and wave load responses in three-dimensional (3D) freak waves. First, in-house code using MATLAB is developed to generate wave parameters which are used for generating short-crested waves and 3D freak waves in the CFD solver. The simulated freak waves are examined and the evolution of freak waves during propagation process is analyzed. Then, ship motions and wave loads considering hydroelastic response in 3D short-crested waves and in 3D freak waves are analyzed. The increase in motions and load responses when ship encountering freak waves is studied quantitatively. This study provides some insights into ship extreme dynamic responses in realistic seaways and in extreme freak waves.

远洋船舶在其使用寿命中可能会遇到罕见的异常浪，这在很大程度上影响了船舶的安全。本文采用双向CFD-FEM流固耦合方法，模拟了船舶在三维畸形波浪中的运动和波浪荷载响应。首先，利用MATLAB编写内部代码，生成CFD求解器中用于生成短峰波和三维畸形波的波参数。对模拟的畸形波进行了检验，分析了畸形波在传播过程中的演化。然后分析了三维短峰波和三维异形波中考虑水弹性响应的船舶运动和波浪荷载。定量研究了船舶遇异常浪时运动和载荷响应的增加。本文的研究为船舶在实际航道和极端异常浪中的极端动力响应提供了一些见解。

引用次数: 0

Lift augmentation by incorporating bend twist coupled composites in flapping wing 在扑翼中加入弯曲扭转耦合复合材料的升力增强

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-10-24 DOI: 10.1016/j.jfluidstructs.2025.104439

Rahul Kumar, Devranjan Samanta, Srikant S. Padhee

Drawing inspiration from the adaptive wing shape of birds in flight, this study introduces a bio-inspired concept for shape adaptation utilizing bend-twist coupling (BTC) in composite laminates. The primary aim of the design optimization is to identify the optimal fibre orientation angles needed to produce the required bending and twisting deformations, which directly contribute to the design's goal of maximizing lift without relying on external mechanisms for twisting. This novel technique increases lift by up to five times compared to a curved bending wing. We have highlighted the vortex dynamics to provide insight into the underlying reasons for such a significant lift increment. In addition, the study presents the Von Mises stress experienced by the wing, offering a comprehensive understanding of the structural behavior. Furthermore, it highlights a significant improvement in efficiency, particularly within the optimal reduced frequency range of 0.25 to 0.4. These findings underscore the potential of this method for future applications in biomimetic drones, unmanned flapping wing vehicles (UFWVs), and other flapping wing-based systems, ultimately paving the way for new advancements in aerodynamics and structural optimization for next-generation aerial vehicle designs.

从鸟类在飞行中的自适应翅膀形状中获得灵感，本研究引入了一种利用弯曲-扭转耦合（BTC）在复合材料层合板中进行形状自适应的仿生概念。设计优化的主要目的是确定产生所需弯曲和扭转变形所需的最佳纤维取向角度，这直接有助于实现在不依赖外部扭转机构的情况下最大化升力的设计目标。与弯曲的机翼相比，这种新技术将升力提高了5倍。我们强调了涡旋动力学，以深入了解如此显著升力增加的潜在原因。此外，该研究还展示了机翼所经历的冯米塞斯应力，提供了对结构行为的全面理解。此外，它还突出了效率的显著提高，特别是在0.25到0.4的最佳降低频率范围内。这些发现强调了该方法未来在仿生无人机、无人扑翼飞行器（UFWVs）和其他基于扑翼的系统中的应用潜力，最终为下一代飞行器设计的空气动力学和结构优化铺平了道路。

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引用次数: 0