Journal of Fluids and Structures最新文献_第9页

Surface bulk cavity formation on flat isotropic plates subjected to near-field underwater explosions 近场水下爆炸作用下平面各向同性板表面体腔的形成

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-17 DOI: 10.1016/j.jfluidstructs.2025.104420

Carlos Javier , Michael Galuska , James LeBlanc , Helio Matos , Arun Shukla

The formation of surface bulk cavities on isotropic flat plates due to the detonation of a near-field underwater explosive (UNDEX) has been computationally investigated. Experiments were performed in an air-backed condition for polycarbonate plates of 6.35 mm thickness, and 12.70 mm thickness, as well as steel plates 12.70 mm in thickness. Moreover, three distances between the explosive and targets were selected. Numerical simulations were performed with the fully coupled Eulerian–Lagrangian fluid structure interaction code Dynamic System Mechanics Advanced Simulation (DYSMAS). Initially, the numerical simulations were validated with the experimental data. Once validated, the numerical simulations were utilized to explore a wide range of structures and standoff distances. Results show that a surface bulk cavity forms on the plate when the centerpoint out of plane velocity of the plate reaches its maximum magnitude while the plate displaces towards the UNDEX gas bubble. Moreover, plates with equal flexural stiffness attained comparable maximum surface bulk cavity volumes. Additionally, the maximum surface bulk cavity volume exponentially decreases as the plate’s flexural stiffness increases. The maximum volume attained by the UNDEX gas bubble is directly related to the timing in which the surface bulk cavity begins to form on the plate. This timing is related to the plate’s flexural stiffness, as well as the plate’s natural frequency. The loading on the plate resulting from the collapse of the surface bulk cavity and the UNDEX gas bubble are influenced by the plate’s flexural stiffness.

本文对近场水下炸药（UNDEX）爆炸后各向同性平板表面体空腔的形成进行了计算研究。在气背条件下对厚度为6.35 mm、12.70 mm的聚碳酸酯板和厚度为12.70 mm的钢板进行了实验。此外，还选择了炸药与目标之间的三个距离。采用欧拉-拉格朗日流固耦合程序DYSMAS进行数值模拟。首先，数值模拟与实验数据进行了验证。一旦验证，数值模拟被用于探索更大范围的结构和距离。结果表明，当板的中心点离面速度达到最大时，板向UNDEX气泡方向位移，在板上形成表面体空腔。此外，具有相同弯曲刚度的板获得了相当的最大表面体积空腔体积。此外，随着板的抗弯刚度的增加，最大表面体腔体积呈指数减小。UNDEX气泡所达到的最大体积与板上表面体腔开始形成的时间直接相关。这个时间与板块的弯曲刚度以及板块的固有频率有关。板的弯曲刚度对板表面容空腔塌陷和UNDEX气泡产生的载荷有一定的影响。

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引用次数: 0

Coupled poro-elastic behavior of hyper-elastic membranes 超弹性膜的耦合孔弹性行为

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-09-13 DOI: 10.1016/j.jfluidstructs.2025.104411

Alexander Gehrke, Zoe King, Kenneth S. Breuer

This study investigates the coupled deformation and flow behavior of thin, hyper-elastic, porous membranes subjected to pressure loading. Using bulge test experiments, optical deformation measurements, and flow rate characterization, we analyze the structural and fluid dynamic responses of membranes with varying material stiffness and porosity patterns. A two-parameter Gent model accurately captures the hyper-elastic deformation, and local stretch analysis reveals non-uniform stretch distributions across the membrane. We find that membrane deformation is primarily governed by material stiffness and pressure, independent of porosity. Pore diameter scales linearly with local stretch, leading to a radial gradient of increasing pore size toward the membrane center. Flow rate scaling is characterized using a discharge coefficient, which accounts for both pore area expansion and pressure losses. Together, these results establish a unified framework that links structural deformation and flow performance in flexible porous membranes, providing robust scaling laws for the design of adaptive, bio-inspired flow-regulating systems.

本研究探讨了压力载荷作用下薄、超弹性多孔膜的耦合变形和流动行为。通过膨胀测试实验、光学变形测量和流速表征，我们分析了不同材料刚度和孔隙率模式下膜的结构和流体动力学响应。双参数Gent模型准确捕获了超弹性变形，局部拉伸分析揭示了膜上不均匀的拉伸分布。我们发现膜的变形主要受材料刚度和压力的影响，而与孔隙率无关。孔径随局部拉伸呈线性增长，导致孔径向膜中心呈径向梯度增大。流量结垢是用流量系数来表征的，流量系数同时考虑了孔隙面积膨胀和压力损失。总之，这些结果建立了一个统一的框架，将柔性多孔膜的结构变形和流动性能联系起来，为自适应、仿生流动调节系统的设计提供了强大的尺度规律。

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引用次数: 0

Blade vibration reduction of a nozzleless radial turbine by casing treatment 机匣处理对无喷嘴径向涡轮叶片减振的影响

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-28 DOI: 10.1016/j.jfluidstructs.2025.104408

Zhaokai Lu , Yingyuan Wang , Mingyang Yang , Xianfeng Wang

High cycle fatigue (HCF) is the most common form of blade failure in nozzleless radial turbines. Current studies on blade vibration reduction primarily focus on the blade design optimization and geometry modifications, typically at the cost of increased rotor weight and reduced aerodynamic performance. This paper investigates a novel flow control method for blade vibration reduction based on casing treatment. Inspired by the generalized force method, casing treatment is proposed to offset the excitation caused by volute. Axial grooves are introduced on the casing (named casing treatment) to reduce blade excitation caused by volute, with particular emphasis on high-expansion-ratio conditions due to the large vibration amplitude. Firstly, the influence of relative position of volute tongue and grooves on blade excitation is investigated via well-validated one-way Fluid-Structure Interaction (FSI) method. Results show that the vibration amplitude can be significantly reduced without sacrificing aerodynamic performance by adjusting the relative position appropriately. Generalized force and flow field analysis reveal that the generalized forces induced by the volute and the groove offset each other when positioned correctly. Secondly, the influence of size parameters of casing treatment on blade excitation is investigated. Two of the parameters only influence the length of generalized force caused by casing treatment rather than the phase, which greatly simplifies and facilitates the optimum design of casing treatment. Numerical results suggest that the blade vibration amplitude can be reduced by up to 94 % at high pressure ratio via the optimum design of the casing treatment. The effect of optimum casing treatment under various pressure ratios is also investigated. The optimum design has satisfied effect at high pressure ratio, but further optimization is required under low pressure ratio conditions. Finally, the effectiveness of the casing treatment is validated via tip-timing experiments, demonstrating a significant reduction in blade amplitude by 48 % under the most critical operating conditions.

高周疲劳（HCF）是无喷嘴径向涡轮叶片最常见的失效形式。目前对叶片减振的研究主要集中在叶片的设计优化和几何形状的修改上，通常是以增加转子重量和降低气动性能为代价的。研究了一种基于机匣处理的叶片减振流动控制方法。受广义力法的启发，提出了用壳体处理来抵消蜗壳引起的激振。在机匣上引入轴向沟槽（称为机匣处理），以减少蜗壳引起的叶片激振，特别强调由于振动幅值大而导致的高膨胀比工况。首先，通过已验证的单向流固耦合（FSI）方法，研究了蜗壳隔舌与沟槽相对位置对叶片激励的影响。结果表明，通过适当调整相对位置，可以在不牺牲气动性能的前提下显著减小振动幅值。广义力和流场分析表明，当定位正确时，蜗壳和槽所产生的广义力相互抵消。其次，研究了机匣处理尺寸参数对叶片激振的影响。其中两个参数只影响套管处理广义力的长度而不影响阶段，大大简化了套管处理的优化设计。数值计算结果表明，通过对机匣处理的优化设计，在高压比下叶片振动幅值可降低94%。研究了不同压力比下最佳套管处理的效果。优化设计在高压比条件下取得了满意的效果，但在低压比条件下仍需进一步优化。最后，通过尖端定时实验验证了套管处理的有效性，结果表明，在最关键的操作条件下，叶片振幅显著降低了48%。

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引用次数: 0

Local-scale experimental investigation of a two-phase cross-flow in a tube bundle and flow-induced vibration: Intermittent/Churn flow 管束内两相交叉流及流致振动的局部尺度实验研究：间歇/搅拌流

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-28 DOI: 10.1016/j.jfluidstructs.2025.104390

Giuseppe Spina , William Benguigui , Guillaume Brillant , Daniele Vivaldi , Catherine Colin

Two-phase cross-flows in tube bundle can induce vibrations. This occurs in many industrial situations, such as nuclear power plant U-tube Steam Generator (SG). With the purpose of gathering high quality data for the validation of multiphase CFD simulation tools, a new experimental apparatus was designed and put in operation. The facility is instrumented for the two-phase air–water flow and tube vibration characterization. This article deals with experimental results in the churn/intermittent two-phase flow conditions. The experimental study was achieved by means of three measurement techniques: high-speed camera, optical dual-tip probe and wire mesh sensor. The behavior of the two-phase flow upstream of the tube bundle, characterized by the continuous generation of large gas structures, is detailed: high-speed camera and wire mesh sensor data reveal the prevalence of dispersed bubbles near the wall and large gas structures in the core region. The rising frequency of the large gas structures could be determined. Profiles of void fraction and gas velocity were measured within the tube bundle.The flow regime map of the experiment is proposed and is correlated with the study of flow-induced tube vibration. It highlights the role played by gas structure size distribution, thus flow pattern in the structural response in intermittent flow regimes with a local-scale characterization of the flow. Finally, the present work is a major contribution to improve and validate local-scale numerical simulation.

管束内两相交叉流动可引起振动。这种情况发生在许多工业场合，例如核电站的u管蒸汽发生器（SG）。为了为多相CFD模拟工具的验证收集高质量的数据，设计了一套新的实验装置并投入运行。该设备用于两相空气-水流动和管道振动表征。本文讨论了搅拌/间歇两相流条件下的实验结果。实验研究采用了高速摄像机、光学双尖端探头和丝网传感器三种测量技术。详细描述了管束上游两相流的行为，其特征是连续产生大型气体结构：高速摄像机和丝网传感器数据揭示了壁面附近分散气泡和核心区域大型气体结构的普遍存在。可以确定大型气体结构的上升频率。测量了管束内空隙率和气速分布。提出了实验流态图，并与流致管振动的研究相联系。它强调了气体结构尺寸分布所起的作用，因此流动模式在间歇性流动状态下的结构响应中具有局部尺度的流动特征。最后，本文的工作为改进和验证局域尺度数值模拟做出了重要贡献。

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引用次数: 0

Enhanced vortex-induced vibration prediction of marine risers using excitation coefficient databases at high Reynolds numbers 基于高雷诺数激励系数数据库的船用隔水管涡激振动增强预测

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-26 DOI: 10.1016/j.jfluidstructs.2025.104406

Jiawei Shen, Pengqian Deng, Shixiao Fu, Xuepeng Fu, Leijian Song, Yuwang Xu

Current methods for predicting vortex-induced vibration (VIV) of marine risers mainly depend on excitation coefficient databases obtained from forced vibration experiments on a rigid cylinder at a low Reynolds number (Re = 1.0E4). However, investigations at higher Reynolds numbers have revealed notable effects on VIV behaviors, resulting in discrepancies when predictions are based on previous experimental databases. To resolve this, forced vibration experiments were carried out on a rigid cylinder model over a Reynolds number range of 5.0E4 to 3.5E5. The acquired data enabled the development of comprehensive excitation coefficient databases covering both subcritical and critical Re regimes. A non-iterative frequency-domain prediction method integrating the updated excitation coefficient databases was proposed and validated through experiments on a flexible riser model. Subsequently, predictive calculations were conducted to investigate the effects of the Reynolds numbers in the excitation coefficient databases on the prediction outcomes. Comparative analysis shows that method based on a higher subcritical Reynolds number (2.0E5) tend to predict larger vibration amplitudes and amplified fatigue damage, whereas those corresponding to critical Reynolds numbers (3.0E5 and 3.5E5) indicate lower amplitudes and reduced fatigue damage. These findings underscore the importance of using excitation coefficient databases that match the relevant Reynolds number conditions to mitigate the risks of overly optimistic or conservative marine riser designs.

目前海洋隔水管涡激振动的预测方法主要依赖于低雷诺数（Re = 1.0E4）下刚性圆柱强制振动实验得到的激励系数数据库。然而，高雷诺数的研究已经揭示了对VIV行为的显着影响，导致基于先前实验数据库的预测存在差异。为了解决这一问题，在雷诺数为5.0E4 ~ 3.5E5的刚性圆柱模型上进行了强迫振动实验。获得的数据使开发涵盖亚临界和临界Re状态的综合激励系数数据库成为可能。提出了一种集成更新的激励系数数据库的非迭代频域预测方法，并通过柔性立管模型进行了实验验证。随后，进行预测计算，研究激励系数数据库中雷诺数对预测结果的影响。对比分析表明，基于较高亚临界雷诺数（2.0E5）的方法预测的振动幅值较大，疲劳损伤放大，而基于临界雷诺数（3.0E5和3.5E5）的方法预测的振动幅值较小，疲劳损伤减小。这些发现强调了使用与相关雷诺数条件相匹配的激励系数数据库来降低过于乐观或保守的海洋立管设计风险的重要性。

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引用次数: 0

Geometrically exact mechanics of pipes conveying fluid with an axially sliding downstream end 具有轴向滑动下游端输送流体的管道的几何精确力学

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-25 DOI: 10.1016/j.jfluidstructs.2025.104402

Amir Mehdi Dehrouyeh-Semnani

In this study, the post-buckling patterns and stability characteristics of hanging and standing soft pipes conveying fluid, with an axially sliding downstream end, are investigated using a new nonlinear geometrically exact model. The mathematical formulation in terms of the rotation angle and lateral displacement, is derived by incorporating the lateral constraint at the downstream end into the geometrically exact model of a cantilevered pipe conveying fluid in terms of the rotation angle. Additionally, a linearized mathematical model of the system around its post-buckling path is established to assess the stability characteristics of post-buckled configurations. To determine the post-buckling patterns and their stability behavior, the shooting scheme in conjunction with the Runge-Kutta finite difference method is utilized. The analysis focuses on both hanging and standing systems, where the downstream end is simply supported and the upstream end may be either clamped or simply supported, taking into account the simultaneous influences of flow velocity and gravity. Furthermore, in the case of the standing system with both ends simply supported, the potential for snap-through buckling is examined. Ultimately, the geometrically exact patterns are compared with those obtained by the original and approximate versions of the nonlinear third-order model.

本文采用一种新的非线性几何精确模型，研究了下游端轴向滑动的悬挂式和直立式软管道的后屈曲模式和稳定性特性。通过将下游端的横向约束纳入悬臂管输送流体的旋转角度几何精确模型，推导出了旋转角度和横向位移的数学表达式。此外，建立了系统后屈曲路径的线性化数学模型，以评估后屈曲构型的稳定性特性。为了确定后屈曲模式及其稳定性行为，采用了结合龙格-库塔有限差分法的射击方案。考虑到流速和重力的同时影响，下端采用简支，上端采用夹紧或简支的悬挂式和立式两种系统进行了分析。此外，在两端简单支撑的站立系统的情况下，检查了卡嗒通屈曲的可能性。最后，将几何上精确的图形与非线性三阶模型的原始和近似版本所得到的图形进行了比较。

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引用次数: 0

Corrigendum to "Flow-induced vibration of an underwater lazy wave cable in unidirectional current" Journal of Fluids and Structures 137 (2025) 104385/YJFLS 104385 https://doi.org/10.1016/j.jfluidstructs.2025.104385 “单向电流下水下懒波电缆的流致振动”《流体与结构学报》137 (2025)104385/YJFLS 104385 https://doi.org/10.1016/j.jfluidstructs.2025.104385的勘误表

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-25 DOI: 10.1016/j.jfluidstructs.2025.104401

R. Moideen , V. Venugopal , J.R. Chaplin , A.G.L. Borthwick

引用次数: 0

Experimental parametric study of a flap-NES passive absorber for post-flutter control 后颤振控制中扑翼- nes被动吸收器的实验参数研究

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-24 DOI: 10.1016/j.jfluidstructs.2025.104405

Jesús García Pérez , Leonardo Sanches , Amin Ghadami , Bogdan I. Epureanu , Guilhem Michon

Aeroelastic instabilities present significant challenges in aircraft design, particularly for novel designs leveraging high aspect ratios and flexible wings to enhance aerodynamic efficiency. These advancements, seen in both high-altitude, high-endurance aircraft and commercial airliners, introduce complexities such as low resonant frequencies and increased susceptibility to aeroelastic instabilities, particularly flutter, which can lead to structural failure. The current certification process requires aircraft to be free from flutter within the operational flight envelope and beyond it, typically with a safety margin of 15% Various strategies have been explored to mitigate flutter and expand the flight envelope. In this work, passive vibration mitigation is applied to an experimental aeroelastic system exhibiting complex aeroelastic instabilities in a wind tunnel. The system consists of a rigid wing mounted on elastic supports with a flap that spans one-third of the wingspan and acts as an innovative nonlinear passive absorber. The setup includes pitch stiffness nonlinearity, which contributes to complex aeroelastic responses such as subcritical flutter and limit cycle oscillations. This solution benefits from aerodynamic damping and adds a very small amount of mass to the system. The main focus of this paper is to assess the influence of flap-NES parameters on aeroelastic behavior and to explore its potential impact on different wing configurations. Results show a delay in the onset of instability up to 34% in airspeed, a suppression of large amplitude vibrations due to stall flutter, and a removal of subcritical behavior.

气动弹性不稳定性对飞机设计提出了重大挑战，特别是对于利用高展弦比和柔性机翼来提高气动效率的新型设计。在高空、高耐力飞机和商用客机上都可以看到这些进步，但这些进步带来了复杂性，如低谐振频率和对气动弹性不稳定性（特别是颤振）的敏感性增加，这可能导致结构失效。目前的认证过程要求飞机在运行飞行包线内外无颤振，通常安全裕度为15%，已经探索了各种策略来减轻颤振和扩大飞行包线。在这项工作中，被动减振应用于一个具有复杂气动弹性不稳定性的风洞实验气动弹性系统。该系统由一个刚性机翼和一个翼展三分之一的襟翼组成，作为一个创新的非线性被动吸收器。该设置包含俯仰刚度非线性，导致复杂的气动弹性响应，如亚临界颤振和极限环振荡。这种解决方案得益于空气动力阻尼，并为系统增加了非常小的质量。本文的主要重点是评估襟翼- nes参数对气动弹性性能的影响，并探讨其对不同机翼构型的潜在影响。结果表明，在空速下，不稳定性的发作延迟高达34%，由于失速颤振引起的大振幅振动得到抑制，并且消除了亚临界行为。

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引用次数: 0

Corrigendum to “FSI simulations of wind gusts impacting an air-inflated flexible membrane at Re = 100,000” [J. Fluids Struct. 109 (2022) 103462] “Re = 100,000时阵风冲击充气柔性膜的FSI模拟”的更正[J]。流体结构。109 (2022)103462 [j]

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-23 DOI: 10.1016/j.jfluidstructs.2025.104384

G. De Nayer, M. Breuer, K. Boulbrachene

引用次数: 0

Snap-through oscillations of an elastic sheet for enhanced heat transfer in dual-channel systems 双通道系统中用于增强传热的弹性片的弹跳振荡

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2025-08-21 DOI: 10.1016/j.jfluidstructs.2025.104407

Jingyu Cui , Yansong Li , Yuzhen Jin , Xianghui Su , Zhaokun Wang

This study explores the use of the snap-through behavior of an elastic sheet as a vortex generator (VG) to enhance heat transfer in a dual-channel system. By leveraging snap-through oscillations, a single sheet clamped at the common wall of the dual channels can simultaneously enhance heat transfer in both channels with a reduced pressure drop. The thermohydraulic performance is analyzed using the immersed boundary-lattice Boltzmann method across varying system parameters. The results demonstrate that for a given Reynolds number (Re), the sheet can operate in either a snap-through mode or dormant mode, depending on its buckled length and bending stiffness (EI*). The snap-through mode achieves superior heat transfer performance, especially at lower bending stiffness, with a thermal efficiency factor (η) of 1.3 at EI* = 0.002, outperforming the wall-clamped flag configuration by 5% and the rigid VG by 14.5%. Comparative analysis reveals that, while the wall-clamped flag configuration is more effective at higher bending stiffness, the proposed VG excels at lower bending stiffness, making these configurations complementary across different applications. The performance of the VG can be further adjusted by modifying the buckled distance of the sheet, with η decreasing as the buckled length increases. Additionally, as Re rises, oscillation-induced flow separation intensifies, further enhancing convective heat transfer. At Re = 1000, η exceeds 1.4, demonstrating robust performance in high-Re regimes. These findings highlight the VG’s potential for tunable and efficient heat transfer enhancement in dual-channel applications.

本研究探讨了利用弹性薄片作为涡流发生器（VG）来增强双通道系统中的传热。通过利用卡通振荡，夹紧在双通道共同壁上的单片材料可以同时增强两个通道的传热，同时降低压降。采用浸入式边界格玻尔兹曼方法分析了不同系统参数下的热工性能。结果表明，在给定雷诺数（Re）下，根据屈曲长度和弯曲刚度（EI*）的不同，薄板可以在卡通模式或休眠模式下工作。卡通模式具有优越的传热性能，特别是在较低的弯曲刚度下，在EI* = 0.002时，热效率系数（η）为1.3，比壁面夹紧的旗杆结构高5%，比刚性的VG结构高14.5%。对比分析表明，虽然壁面夹紧标志结构在较高的弯曲刚度下更有效，但所提出的VG在较低的弯曲刚度下表现出色，使这些结构在不同的应用中互补。通过改变板材的屈曲距离，可以进一步调节卷材的性能，η随屈曲长度的增加而减小。此外，随着Re的升高，振荡引起的流动分离加剧，进一步增强了对流换热。在Re = 1000时，η值超过1.4，在高Re状态下表现出稳健的性能。这些发现突出了VG在双通道应用中可调和高效传热增强的潜力。

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引用次数: 0