Journal of Fluids and Structures最新文献_第8页

Stably biased gap flow between two flapping and stationary short cantilevers in close proximity 两个拍动和固定短悬臂梁之间的稳定偏置间隙流

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-29 DOI: 10.1016/j.jfluidstructs.2025.104432

Yongpu Wang , Yanyan Liu , Michael David Atkins , Tian Jian Lu , Tongbeum Kim

Contrary to previously known physics about fluid motion around two side-by-side circular cylinders, this study has demonstrated stably biased gap flow when excited by a flapping and stationary cantilever pair - the gap flow is only deflected towards the flapping cantilever (without switching). Mechanisms for this behavior were presented in this study. To this end, flow visualization and spectral analysis of time-resolved data from hot-wire anemometers and the piezoelectric mount of a flapping cantilever were carried out. Furthermore, particle image velocimetry was conducted to map instantaneous and time-averaged velocity and vorticity fields. During measurements, a center-to-center spacing normalized by cantilever diameter (T/D, pitch ratio) was systematically varied in the Reynolds number range of 1800 ≤ Re_D ≤ 13,000. We demonstrated that the Kelvin-Helmholtz (K-H) instability of shear layers separated from the flappable cantilever was intensified due to flapping, consequently inciting the earlier onset of Kármán vortices (evolved from K-H vortices) than those behind the stationary cantilever. Thereafter, an earlier velocity recovery developed, generating a transverse pressure gradient towards the flapping cantilever and subsequent upstream penetration (i.e., potential effect). The gap flow then became stably pushed towards the flapping cantilever.

与先前已知的围绕两个并排的圆柱体的流体运动的物理学相反，这项研究已经证明了当被扑动和静止的悬臂对激发时，稳定的偏置间隙流-间隙流仅向扑动悬臂偏转（没有切换）。本研究提出了这种行为的机制。为此，对热线风速计和扑动悬臂的压电支架的时间分辨数据进行了流动可视化和频谱分析。此外，采用粒子图像测速技术绘制瞬时场和时均速度场和涡度场。在测量过程中，通过悬臂直径（T/D，节距比）归一化的中心间距在1800≤ReD≤13,000的雷诺数范围内系统地变化。我们证明了从可扑动悬臂中分离出来的剪切层的开尔文-亥姆霍兹（K-H）不稳定性由于扑动而加剧，从而激发Kármán涡旋（从K-H涡旋演变而来）比静止悬臂后的涡旋更早开始。随后，一个较早的速度恢复发展，产生一个横向压力梯度，指向扑翼悬臂和随后的上游穿透（即潜在效应）。间隙流被稳定地推向扑翼悬臂梁。

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引用次数: 0

On the oscillatory behavior of two pendulum-like tandem circular slender cylinders 两个类摆串联细长圆柱的振动特性研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-29 DOI: 10.1016/j.jfluidstructs.2025.104424

Patrick Batista Habowski , Sergio Viçosa Möller , Adriane Prisco Petry , Atef Mohany

This experimental study investigates the flow–structure interaction of two identical tandem slender cylinders subjected to cross-flow in a wind tunnel. The upstream and downstream cylinders were mounted in a pendulum-like configuration, allowing only transverse oscillation with matching natural frequencies, and were also tested in a fixed configuration for comparison purposes. All experiments were performed at spacing ratios ranging from 2.0 to 7.5, within a Reynolds number range of 16,000 to 22,000. Lateral displacements were recorded using a high-speed camera, and flow structures were analyzed using Particle Image Velocimetry (PIV). The primary objective was to correlate the observed flow dynamics from the PIV results with the oscillatory behavior of the cylinders. The results show that oscillations occurred for all investigated spacing ratios, with the most significant oscillations observed at a spacing ratio of 2.0 and a distinctive pattern with extreme amplitudes at a spacing ratio of 3.5. Cross-correlation of the Discrete Wavelet Transform of the vibration response reveals that the vibration of the downstream cylinder are influenced by the wake of the upstream cylinder, with its amplitude remaining enveloped within the wake of the upstream cylinder. The flow structure driving the oscillatory behavior indicates that the vibrations of the cylinders are predominantly governed by wake-induced vibration, except for the case of

L / D = 3.5

, where a galloping-like instability was observed—a mechanism not previously reported for this configuration. The phenomenon described in this paper presents potential opportunity for energy harvesting applications.

本实验研究了两个相同的细长串列圆柱体在风洞中横流作用下的流-结构相互作用。上游和下游圆柱体安装在摆状结构中，只允许具有匹配的固有频率的横向振荡，并且还在固定配置中进行了测试以进行比较。所有的实验都在2.0到7.5的间距比范围内进行，雷诺数范围为16000到22000。使用高速摄像机记录横向位移，并使用粒子图像测速仪（PIV）分析流动结构。主要目的是从PIV结果中观察到的流动动力学与气缸的振荡行为相关联。结果表明，在不同的间距比下，振荡现象都有发生，当间距比为2.0时振荡现象最显著，当间距比为3.5时振荡特征明显，且振幅极值。振动响应的离散小波变换相互关联表明，下游圆柱的振动受到上游圆柱尾迹的影响，其幅值仍被上游圆柱尾迹包裹。驱动振荡行为的流动结构表明，除了L/D=3.5的情况外，气缸的振动主要由尾迹引起的振动控制，在这种情况下观察到类似飞奔的不稳定性，这是一种以前没有报道过的机制。本文所描述的现象为能量收集应用提供了潜在的机会。

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引用次数: 0

Study on the high-speed shallow-angle water entry of cylinders with varying densities 变密度圆柱高速浅角入水研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-27 DOI: 10.1016/j.jfluidstructs.2025.104429

Xuepu Yan , Shuai Sun , Mo Zhu , Tengfei Xu , Pengfei Liu , Zeqing Guo

An investigation into the transient fluid-structure interactions during the high-speed (600 m/s) shallow-angle (8°) water entry of cylindrical projectiles with varying densities (2.7-16.1 g/cm³) is presented. The fundamental mechanisms governing cavity dynamics and projectile stability are revealed using three-dimensional computational fluid dynamics (CFD) simulations, which are validated by synchronized high-speed imaging. The key findings demonstrate that asymmetric wetting of the cylinder’s head during the early stage of water entry induces a critical head-down moment that governs subsequent hydrodynamic behavior. Three distinct fluid dynamic mechanisms are identified: 1) Delayed upper cavity formation accompanied by asymmetric cavity expansion; 2) Splash convergence producing distinct upward and downward jets, with the latter inducing localized cavity collapse upon impacting the wall; and 3) Pressure redistribution at the head end caused by variations in angle of attack, which generates restoring moments through asymmetric flow patterns. Density-dependent kinematic analysis reveals that within the same range of horizontal displacement, low-density cylinders (ρ≤4.1 g/cm³) undergo multiple tail slaps, whereas high-density cylinders (ρ≥7.2 g/cm³) achieve rotational stabilization through head-end restoring moments prior to tail slap initiation. Quantitative analysis shows that increasing the density from 2.7 to 16.1 g/cm³ reduces the maximum angular deflection by 89.43 % and the accumulated trajectory curvature by 42.83 %. These findings establish material density as the primary control parameter for ricochet prevention during shallow-angle water entry.

研究了不同密度（2.7 ~ 16.1 g/cm³）圆柱形弹丸高速（600 m/s）浅角（8°）入水过程中的瞬态流固耦合。利用三维计算流体动力学（CFD）模拟揭示了控制空腔动力学和弹丸稳定性的基本机制，并通过同步高速成像对其进行了验证。关键发现表明，在水进入的早期阶段，水缸头部的不对称润湿导致了一个关键的头部下降时刻，该时刻控制着随后的水动力行为。确定了三种不同的流体动力学机制：1)上部空腔的延迟形成伴随着不对称的空腔扩张；2)飞溅辐合产生明显的向上和向下射流，向下射流在撞击壁面时引起局部空腔塌陷；3)攻角变化引起的头部压力重分布，通过不对称流型产生恢复力矩。与密度相关的运动学分析表明，在相同的水平位移范围内，低密度圆柱体（ρ≤4.1 g/cm³）经历多次尾扇，而高密度圆柱体（ρ≥7.2 g/cm³）通过尾扇开始前的头部恢复力矩实现旋转稳定。定量分析表明，将密度从2.7 g/cm³增加到16.1 g/cm³，最大角偏转减少89.43%，累计轨迹曲率减少42.83%。这些研究结果表明，材料密度是浅角进水过程中防止跳弹的主要控制参数。

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引用次数: 0

A low-cost morphing vehicle design for enhanced aerodynamic performance 一种低成本的可变形飞行器设计，增强了气动性能

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-25 DOI: 10.1016/j.jfluidstructs.2025.104422

Sina Kazemipour, Peng Zhang

Mid- and large-size road vehicles are responsible for high levels of green-house gas emissions, due to their poor aerodynamic designs. To alleviate this environmental and health risk, we propose a low-cost, noninvasive morphing vehicle design toward improved aerodynamic efficiency and reduced emissions. Using a generic pickup truck as the base geometry, morphing is accomplished by retrofitting a flexible structure over its cargo bed region, enabling active deformation and interaction with the airflow. The shape morphing process is optimized through a combined parametric genetic algorithm – computational fluid dynamics framework, enabling continuous morphing across a range of driving speeds. The optimal structural shapes lead to a reduction in the aerodynamic drag force between 8.7% and 10.1%. Analysis of the airflow physics reveals that the morphing structure compresses the size of the circulation bubble and reduces the strength of the counter-rotating flow structures in the wake, resulting in increased wake pressure and decreased drag force. Remarkably, the morphing structure not only reduces the drag on the base vehicle geometry but also elicits a negative drag force on itself. This non-invasive morphing vehicle design concept could transform the automotive industry by enhancing fuel economy and reducing emissions for existing vehicle models.

中型和大型公路车辆由于其糟糕的空气动力学设计，造成了高水平的温室气体排放。为了减轻这种环境和健康风险，我们提出了一种低成本、无创的变形车辆设计，以提高空气动力学效率和减少排放。采用通用皮卡作为基础几何形状，通过在其货床区域上改装一个灵活的结构来实现变形，从而实现主动变形和与气流的相互作用。形状变形过程通过组合参数遗传算法-计算流体动力学框架进行优化，实现在一系列驾驶速度下的连续变形。优化后的结构形状可使气动阻力降低8.7% ~ 10.1%。气流物理分析表明，变形结构压缩了循环气泡的大小，降低了尾迹中逆旋流结构的强度，导致尾迹压力增大，阻力减小。值得注意的是，变形结构不仅减少了对车辆基础几何形状的阻力，而且还引起了对自身的负阻力。这种非侵入式变形汽车设计理念可以通过提高现有车型的燃油经济性和减少排放来改变汽车行业。

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引用次数: 0

Hydrodynamic behavior of an offshore OWC power station under dam-break flows: Numerical and experimental study 溃坝水流作用下近海OWC电站的水动力特性：数值与试验研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-25 DOI: 10.1016/j.jfluidstructs.2025.104426

Shiqi Pan , Haochen Zhang , Jing Geng , Xuanlie Zhao

The hydrodynamic behavior of a three-dimensional oscillating water column (OWC) device subjected to dam-break flow incidents was investigated using numerical and experimental methods. Load characteristics and flow field distributions were analyzed under various opening ratios of the air chamber and angles of incident flow. Numerical results were validated against experimental measurements of impact loads and water surface elevation at a 45° incident angle, and extended to six additional incident angles: 0°, 15°, 30°, 60°, 75°, and 90°. The peak impact load and air chamber pressure occurred at 90°, both decreasing as the incident angle varied to 0°. The peak horizontal resultant force decreased by 43.4 %, 55.3 %, and 65.9 % at 60°, 45°, and 30°, respectively, while peak air pressure decreased by up to 68 % at 0°. Loads on internal and external walls were of similar magnitudes, highlighting the importance of considering internal wall forces in structural design. Flow field analysis revealed complex flow contours and an inclined water surface inside the chamber, which became more pronounced as the incident angle decreased. Moreover, increasing the opening ratio of the air chamber significantly reduced peak impact loads and air pressure, especially in the range of 0 % to 3.5 %. However, larger opening ratios may reduce energy capture efficiency. Thus, selecting an appropriate opening ratio that balances load reduction with energy capture efficiency is crucial for OWC design.

采用数值与实验相结合的方法，研究了三维振荡水柱装置在溃坝水流作用下的水动力特性。分析了不同气室开度比和入射气流角度下的负载特性和流场分布。数值结果与45°入射角下的冲击载荷和水面高度的实验测量结果进行了验证，并扩展到6个额外的入射角：0°、15°、30°、60°、75°和90°。冲击载荷和气室压力峰值出现在90°角处，随入射角增大至0°而减小。在60°、45°和30°时，峰值水平合力分别下降了43.4%、55.3%和65.9%，而在0°时，峰值气压下降了68%。内墙和外墙的荷载大小相似，突出了在结构设计中考虑内墙力的重要性。流场分析表明，随着入射角的减小，射流腔内流动轮廓复杂，水流表面呈倾斜趋势。此外，增加气室的开度比可以显著降低峰值冲击载荷和空气压力，特别是在0%至3.5%的范围内。然而，较大的开口比可能会降低能量捕获效率。因此，选择一个合适的开口比，平衡负荷减少和能量捕获效率是OWC设计的关键。

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引用次数: 0

Shifting aeroacoustic source mechanisms of a transversely oscillating cylinder in lock-in region at various Mach numbers 不同马赫数下锁闭区横向振荡圆柱体移动气动声源机理

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-23 DOI: 10.1016/j.jfluidstructs.2025.104425

Fangcheng Shi , Hongpeng Liu , Dongrun Liu , Tiantian Wang

Direct numerical simulation of the aerodynamic noise generated by a flow past a transversely oscillating cylinder is conducted to investigate the effect of Mach number on the aeroacoustic characteristics. The results indicate that the coupling between the oscillating motion and vortex shedding in the lock-in region leads to a distribution of the surface pressure pulsation time derivative with four distinct peaks. The intensity of the radiated noise from the oscillating cylinder in the lock-in region is reduced compared to the stationary case. Although the oscillating frequency associated with this noise reduction is insensitive to Mach number, the reduction effect weakens at high Mach numbers. Furthermore, as the Mach number increases, the sound directivity at the lock-in boundary transitions from a figure-eight configuration to a butterfly-like configuration, featuring distinct lobes both upstream and downstream. To illustrate the changes in noise, the key finding is the modified scaling law governing noise intensity in relation to Mach number for the oscillating cylinder: it shifts from

M^{2.5}

to

M^{3.5}

, characteristic of quadrupole sources. This alteration is further analyzed by applying the Ffowcs Williams-Hawkings equation to separate the contributions of different noise sources, and utilizing spectral proper orthogonal decomposition to extract the dominant coherent structures responsible for the oscillating cylinder at the lock-in boundary at high Mach numbers.

为了研究马赫数对横摆圆柱气流噪声的影响，对横摆圆柱气流噪声进行了直接数值模拟。结果表明：锁相区振荡运动与旋涡脱落的耦合作用导致表面压力脉动时间导数呈四个明显的峰值分布；与静止情况相比，锁相区振荡圆柱体的辐射噪声强度减小。虽然与此降噪相关的振荡频率对马赫数不敏感，但在高马赫数时降噪效果减弱。此外，随着马赫数的增加，锁定边界处的声指向性从8字形结构转变为蝴蝶状结构，上游和下游都有明显的叶状结构。为了说明噪声的变化，关键的发现是控制噪声强度与振荡圆柱体马赫数相关的修正比例定律：它从M2.5转移到M3.5，这是四极源的特征。利用Ffowcs williams - hawkins方程分离不同噪声源的贡献，并利用频谱固有正交分解提取高马赫数下锁相边界处导致圆柱振荡的主导相干结构，进一步分析了这种变化。

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引用次数: 0

Aerodynamic admittance and dynamics of an open-grown tree 开放生长树木的空气动力导纳和动力学

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-23 DOI: 10.1016/j.jfluidstructs.2025.104409

Xiaonan Wang , Jakob Mann , Ebba Dellwik , Nikolas Angelou

Enhancing our understanding of the structural response of trees exposed to wind loading is important, since the knowledge of their aerodynamic behaviour is necessary for a realistic risk assessment of tree damage during extreme wind conditions. Here, we first present an analytical model of the aerodynamic admittance function that relates the turbulence fluctuations of the wind at a single point to their spatial average over the crown’s frontal area. The latter is responsible for the wind-induced bending moments at the base of a tree’s stem. We employ the aerodynamic admittance function to model the dynamic structural response of an open-grown oak tree. The analysis is performed along two axes to express both the longitudinal and transverse response with respect to the mean wind direction. The resulting predictions are compared with strain gauge observations taken at the lower part of the stem. The presented framework shows that the spatial averaging over the crown’s frontal area has a stronger effect on the tree’s movements in the streamwise wind direction compared to the spanwise direction. Further, the aerodynamic damping is also stronger in the streamwise direction and generally correlates positively with the inflow wind speed.

加强我们对树木在风荷载下的结构响应的理解是很重要的，因为了解它们的空气动力学行为对于在极端风条件下对树木损伤进行现实的风险评估是必要的。在这里，我们首先提出了一个气动导纳函数的解析模型，该模型将风在单点处的湍流波动与其在冠锋面区域的空间平均值联系起来。后者负责风在树干底部引起的弯矩。我们采用空气动力学导纳函数来模拟开放式橡树的动力结构响应。分析沿两个轴进行，以表示相对于平均风向的纵向和横向响应。所得到的预测结果与在阀杆下部采用的应变计观测结果进行了比较。所提出的框架表明，相对于树幅方向，树冠锋面区域的空间平均对树在顺流风向上的运动有更强的影响。此外，气动阻尼在顺流方向上也更强，通常与入流风速呈正相关。

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引用次数: 0

Sequential learning based PINNs to overcome temporal domain complexities in unsteady flow past flapping wings 基于序贯学习的非定常流场扑翼飞行时域复杂性研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-23 DOI: 10.1016/j.jfluidstructs.2025.104421

Rahul Sundar , Didier Lucor , Sunetra Sarkar

For a data-driven and physics combined modeling of unsteady flow systems with moving immersed boundaries, Sundar et al. (Sundar et al. 2024) introduced an immersed boundary-aware (IBA) framework, combining Physics-Informed Neural Networks (PINNs) and the immersed boundary method (IBM). This approach was beneficial because it avoided case-specific transformations to a body-attached reference frame. Building on this, we now address the challenges of long time integration in velocity reconstruction and pressure recovery by extending this IBA framework with sequential learning strategies. Key difficulties for PINNs in long time integration include temporal sparsity, long temporal domains and rich spectral content. To tackle these, a moving boundary-enabled PINN is developed, proposing two sequential learning strategies: - a time marching with gradual increase in time domain size, training a monolithic PINN and - a time decomposition which divides the temporal domain into smaller segments, training a PINN over each subdomains and combining them together. While the former approach may struggle with error accumulation over long time domains, the latter one, eventually combined with transfer learning, effectively reduces error propagation and computational complexity. The key findings for modeling of incompressible unsteady flows past a flapping airfoil include: - for quasi-periodic flows, the time decomposition approach with preferential spatio-temporal sampling improves accuracy and efficiency for pressure recovery and aerodynamic load reconstruction, and, - for long time domains, decomposing it into smaller temporal segments and employing multiple sub-networks, simplifies the problem ensuring stability and reduced network sizes. This study highlights the limitations of traditional PINNs for long time integration of flow-structure interaction problems and demonstrates the benefits of decomposition-based strategies for addressing error accumulation, computational cost, and complex dynamics.

对于具有移动浸入边界的非定常流动系统的数据驱动和物理结合建模，Sundar等人（Sundar et al. 2024）引入了浸入边界感知（IBA）框架，结合了物理信息神经网络（pinn）和浸入边界方法（IBM）。这种方法是有益的，因为它避免了特定于案例的对附加主体的参考框架的转换。在此基础上，我们现在通过使用顺序学习策略扩展IBA框架，解决了在速度重建和压力恢复方面的长期集成挑战。时间稀疏性、长时域和丰富的谱内容是长时间集成的关键问题。为了解决这些问题，开发了一个移动边界支持的PINN，提出了两种顺序学习策略：-随着时域大小逐渐增加的时间行进，训练单个PINN； -将时域分成更小的片段的时间分解，在每个子域上训练一个PINN并将它们组合在一起。前一种方法可能会在长时间域上与错误积累作斗争，而后一种方法最终与迁移学习相结合，有效地减少了错误传播和计算复杂度。对扑翼型不可压缩非定常流场建模的主要发现包括：—对于准周期流，采用优先时空采样的时间分解方法提高了压力恢复和气动载荷重建的准确性和效率；—对于长时间域，将其分解为更小的时间段并采用多个子网络，简化了确保稳定性和减小网络尺寸的问题。本研究强调了传统的pinn在长时间集成流-结构相互作用问题上的局限性，并展示了基于分解的策略在解决误差积累、计算成本和复杂动力学方面的优势。

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引用次数: 0

Active flow control of vertical-axis wind turbines: Insights from large-eddy simulation and finite-time resolvent analysis 垂直轴风力涡轮机的主动流动控制：来自大涡模拟和有限时间解析分析的见解

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-22 DOI: 10.1016/j.jfluidstructs.2025.104410

Lucas Feitosa de Souza, Renato Fuzaro Miotto, William Roberto Wolf

Active flow control is applied to improve the aerodynamic performance of a NACA0018 airfoil operating as a single-bladed vertical axis wind turbine (VAWT). Results computed by wall-resolved large-eddy simulations (LES) highlight the detrimental effects of the dynamic stall vortex (DSV) and trailing-edge vortex (TEV) on turbine efficiency, primarily through increased drag and energy loss. The proposed flow control strategy effectively delays flow separation and suppresses large-scale vortex formation, particularly at moderate actuation frequencies. The control parameters are grounded in bi-global stability and finite-time resolvent analyses. These techniques identify the excitation of coupling modes between shear layer and wake instabilities as a mechanism for promoting flow reattachment and preventing vorticity accumulation, ultimately leading to enhanced torque production. The control strategy is energy-efficient, consuming only 1% of the turbine’s output power while yielding substantial aerodynamic performance gains. These findings demonstrate the promise of physics-informed active flow control in mitigating dynamic stall and advancing the design of next-generation VAWTs.

主动流动控制应用于改善NACA0018翼型作为单叶片垂直轴风力涡轮机（VAWT）的气动性能。壁面分辨大涡模拟（LES）的计算结果强调了动态失速涡（DSV）和尾缘涡（TEV）对涡轮效率的不利影响，主要是通过增加阻力和能量损失来实现的。所提出的流动控制策略有效地延缓了流动分离，抑制了大规模涡的形成，特别是在中等驱动频率下。控制参数基于双全局稳定性和有限时间解析分析。这些技术确定了剪切层和尾流不稳定性之间耦合模式的激励是促进流动再附着和防止涡量积累的机制，最终导致扭矩产生的增强。该控制策略是节能的，仅消耗涡轮机输出功率的1%，同时产生可观的空气动力学性能增益。这些发现表明，基于物理信息的主动流量控制技术有望缓解动态失速，并推进下一代vawt的设计。

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引用次数: 0

Coupled fluid–structure simulations of a cantilever rod in water turbulent axial flow with different CFD approaches 用不同CFD方法对悬臂杆在水湍流轴流中的耦合流固耦合模拟

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-18 DOI: 10.1016/j.jfluidstructs.2025.104412

Daniele Vivaldi, Roxan Pulicani

Fluid–structure numerical simulations of an experimental campaign by Cioncolini et al. of a cantilever rod in water axial flow were performed. The experimental configuration aims at representing a nuclear fuel rod, in terms of hydraulic diameter. Water velocity profiles and structure vibrations were measured experimentally. Two of the experimental tests were simulated numerically, one at Re=1.5

\cdot

10⁴ and one at Re=1.9

\cdot

10⁴. Different CFD approaches were tested, using code_Saturne: a wall-resolved two-equation linear viscosity model (k-

ω

-SST), two wall-modeled Reynolds stress models (SSG and LRR), a wall-resolved Reynolds stress model (EBRSM) and a wall-resolved hybrid URANS/LES model (DDES). The structure was simulated through a one-dimensional finite element Euler–Bernoulli beam model. A 2-way coupling was implemented between the two solvers, with an Arbitrary Lagrangian Eulerian approach. Unexpectedly, wall-modeled Reynolds-stress models were found to calculate higher amplitudes of vibration than the higher-resolution EBRSM and DDES. The frequency domain analysis allowed to identify high energy flow velocity and flow-induced force harmonics at relatively low frequency calculated by LRR and SSG, not present in the EBRSM and DDES results, which explain the numerical results in terms of vibration response. This specific behavior of LRR and SSG seems to be linked to the wall function boundary condition. LRR and SSG calculate a rms amplitude of vibration close to the experiments, whereas EBRSM and DDES underestimate them by a factor of 2.5. A hypothetical small permanent deformation (4% of the hydraulic diameter) of the rod was simulated and found to increase the calculated vibration amplitudes by a factor of 2. 1-way coupling was also tested to assess the influence of damping and added mass on the results.

本文对Cioncolini等人的悬臂杆在水轴流中的实验运动进行了流固耦合数值模拟。实验配置的目的是代表一个核燃料棒，在水力直径方面。实验测量了水的速度分布和结构振动。分别对Re=1.5⋅104和Re=1.9⋅104进行了数值模拟。使用code_Saturne测试了不同的CFD方法：壁面解析双方程线性黏度模型（k-ω-SST）、两种壁面解析雷诺应力模型（SSG和LRR）、壁面解析雷诺应力模型（EBRSM）和壁面解析混合URANS/LES模型（DDES）。采用一维有限元欧拉-伯努利梁模型对结构进行了数值模拟。采用任意拉格朗日欧拉方法，实现了两个求解器之间的双向耦合。出乎意料的是，墙型雷诺应力模型比高分辨率的EBRSM和DDES计算出更高的振动幅值。频域分析可以识别出LRR和SSG计算的相对低频的高能量流速度和流激力谐波，而EBRSM和DDES结果中没有，这从振动响应的角度解释了数值结果。LRR和SSG的这种特殊行为似乎与壁函数边界条件有关。LRR和SSG计算的均方根振动幅值接近实验值，而EBRSM和DDES低估了实验值的2.5倍。模拟了一个假设的杆的小永久变形（液压直径的4%），并发现计算出的振动幅值增加了2倍。还测试了单向耦合，以评估阻尼和附加质量对结果的影响。

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引用次数: 0