Journal of Fluids and Structures最新文献

Experimental study on vortex-induced vibrations of a circular cylinder elastically supported by realistic nonlinear springs: Vibration response 实际非线性弹簧弹性支撑圆柱涡激振动的实验研究：振动响应

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-02 DOI: 10.1016/j.jfluidstructs.2024.104233

Yawei Zhao , Zhimeng Zhang , Chunning Ji , Weilin Chen , Jiahang Lv , Hanghao Zhao

This study presents an experimental investigation into the vortex-induced vibrations (VIV) of a single circular cylinder supported by various nonlinear springs. Unlike previous studies focused on systems satisfying the Duffing equation, this study explores a realistic scenario with nonlinear restoring forces derived from different magnet configurations. Experiments were conducted in a low-speed circulating water flume across a Reynolds number range of Re = 232-20930, a mass ratio (m*) ranging from 3.39 to 5.55, and a nonlinear strength coefficient (λ) from -1.48 to 1.70. The results demonstrated that predicted nonlinear VIV amplitudes using linear VIV data align well with experimental observations, validating the applicability of the prediction theory (Mackowski and Williamson, PoF, 2013) to general nonlinear systems. An equivalent reduced velocity (U_eq) was introduced to rescale vibration responses, effectively collapsing the envelopes for linear and hardening nonlinear systems, although shifts to higher U_eq values were observed for softening systems. A detailed analysis of the nonlinear coefficient's impact on VIV characteristics, including amplitude, frequency, phase lag, and displacement history, identified four distinct VIV response groups: softening, weak hardening, intermediate hardening, and strong hardening nonlinear VIV. A notable finding is the presence of two lock-in regions in nonlinear VIV responses, characterized by superharmonic synchronization, and multiple-value sections and gaps in vibration envelopes at specific transitions. These behaviors are attributed to variations in the natural frequency (f_n(A*)) with vibration amplitude. This study provides valuable insights into the complex dynamics of general nonlinear VIV, offering a foundation for future research and practical applications.

本文对不同非线性弹簧支承的单圆柱涡激振动进行了实验研究。不同于以往的研究集中在满足Duffing方程的系统上，本研究探索了一个具有非线性恢复力的现实场景，这些力来自不同的磁铁结构。实验在低速循环水水槽中进行，雷诺数Re = 232 ~ 20930，质量比m*为3.39 ~ 5.55，非线性强度系数λ为-1.48 ~ 1.70。结果表明，使用线性VIV数据预测的非线性VIV振幅与实验观测结果很好地吻合，验证了预测理论（Mackowski和Williamson， PoF, 2013）对一般非线性系统的适用性。引入等效降速（Ueq）来重新调整振动响应，有效地压缩了线性和硬化非线性系统的包络层，尽管在软化系统中观察到更高的Ueq值。详细分析了非线性系数对涡激振动特性的影响，包括振幅、频率、相位滞后和位移历史，确定了四种不同的涡激振动响应组：软化、弱硬化、中等硬化和强硬化非线性涡激振动。一个值得注意的发现是，非线性激振响应中存在两个锁定区域，其特征是超谐波同步，以及在特定过渡时振动包络中的多值部分和间隙。这些特性归因于固有频率（fn(A*)）随振动幅值的变化。本研究为研究一般非线性涡激振动的复杂动力学提供了有价值的见解，为今后的研究和实际应用奠定了基础。

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引用次数: 0

On the mechanism of frequency lock-in vibration of airfoils during pre-stall conditions 预失速状态下翼型频率锁定振动机理研究

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-12-01 DOI: 10.1016/j.jfluidstructs.2024.104227

Jingge Quan , Sijia Zhang , Chuanqiang Gao , Zhengyin Ye , Weiwei Zhang

Potential frequency lock-in vibration can frequently occur in aircraft flying at separated flow conditions during take-off and landing stages, severely threatening the safety of the aircraft. A deeper understanding of the lock-in phenomenon in pre-stall (steady separated flow) conditions is necessary to improve aircraft reliability and safety. In this paper, a reduced-order model (ROM) for the pitching NACA0012 airfoil in steady separated flow is established. A linear aeroelastic model is then obtained by coupling the ROM with the structural dynamical equation with the pitching degree of freedom, and it is verified by the computational fluid dynamics/computational structural dynamics (CFD/CSD) simulation. Next, the mechanism of frequency lock-in vibration is revealed by the ROM-based aeroelastic model of different structural natural frequencies. Results from the complex eigenvalue analysis indicate that the instability can be divided into two patterns. At high frequencies, the flutter frequency locked onto the natural frequency of the structure, and it is dominated by the instability of structural mode. At low frequencies, the flutter frequency follows the fluid characteristic frequency, which is dominated by the instability of the fluid mode. Finally, the effects of the angle of attack and mass ratio are investigated. The damping of dominant fluid mode decreases with the increase of angle of attack, which affects the structural mode through coupling effects. Therefore, the angle of attack influences the upper boundary of the coupling system’s instability (high frequency boundary). On the contrary, the mass ratio mainly influences the lower boundary of instability (low frequency boundary), because fluid mode becomes unstable at low frequencies merely when the mass ratio is relatively low.

飞机在起飞和降落阶段的分离流条件下飞行时，经常会发生潜在的频率锁定振动，严重威胁飞机的安全。为了提高飞机的可靠性和安全性，有必要深入了解预失速（稳定分离流）条件下的锁定现象。本文建立了俯仰NACA0012翼型定常分离流动的降阶模型。将ROM与具有俯仰自由度的结构动力学方程耦合得到线性气动弹性模型，并通过计算流体动力学/计算结构动力学（CFD/CSD）仿真对其进行了验证。其次，利用基于rom的不同结构固有频率的气动弹性模型揭示了频率锁定振动的机理。复特征值分析结果表明，不稳定性可分为两种模式。在高频率下，颤振频率锁定在结构固有频率上，由结构模态失稳主导。在低频时，颤振频率遵循流体特性频率，主要受流体模态的不稳定性影响。最后，研究了迎角和质量比的影响。随着迎角的增大，主导流体模态阻尼减小，通过耦合效应影响结构模态。因此，迎角影响耦合系统失稳的上边界（高频边界）。相反，质量比主要影响不稳定的下边界（低频边界），因为只有当质量比较低时，流体模式才会在低频处变得不稳定。

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引用次数: 0

VIV mechanisms of a non-streamlined bridge deck equipped with traffic barriers 装有交通护栏的非流线型桥面的 VIV 机制

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-25 DOI: 10.1016/j.jfluidstructs.2024.104195

Bernardo Nicese , Antonino Maria Marra , Gianni Bartoli , Claudio Mannini

Vortex-induced vibration (VIV) has been addressed in the literature mostly for quasi-streamlined and shallow π-deck sections, typical of long-span bridges, since the latter are particularly prone to wind-induced oscillations. In contrast, although full-scale observations demonstrate that even steel-box girder bridges, usually characterized by a shorter span length if compared to suspension and cable-stayed bridges, can experience a violent VIV response, systematic studies for these bluffer cross-section geometries are less frequent. In addition, the aerodynamic optimization of non-structural additions (barriers, screens, fairings) is rarely carried out for this bridge typology. Therefore, a wind tunnel investigation is conducted on a non-streamlined box-girder sectional model (inspired by the Volgograd Bridge, Russia) equipped with two typologies of traffic barriers giving rise to a large ratio of barrier height to deck width. A realistic range of angles of attack (from −3° to 3°) are considered, and static forces, aeroelastic vibrations and wake velocity fluctuations are measured. A large and even unexpected variability in the vibration amplitude and lock-in curve pattern is found, emphasizing the possible existence of competing excitation mechanisms. Indeed, low-porosity barriers can alter the characteristics of vortex shedding, in particular creating a cavity on the upper side of the deck, which is known to foster the impinging-shear-layer instability, as in H-shaped sections. This vortex-shedding mechanism may co-exist with Kármán-vortex shedding and may be responsible for significant anticipation of the VIV onset compared to the predictions based on the Strouhal number measured during static tests. The intensity of a secondary excitation mechanism and its interaction with the dominant mechanism strongly depend on the angle of attack and is largely responsible for profound changes in the VIV bridge response, both in terms of qualitative pattern and peak amplitude. In some cases, the tracks of these competing vortex-shedding mechanisms are even clearly visible in the VIV response curves of the tested bridge model. Finally, the wind tunnel results are also reconsidered based on the quasi-steady theory, highlighting some, even qualitative, discrepancies.

涡流诱导振动（VIV）在文献中主要针对大跨度桥梁的典型准流线型和浅π甲板截面，因为后者特别容易受风诱导振动的影响。与此相反，虽然全尺寸观测结果表明，与悬索桥和斜拉桥相比跨度较短的钢箱梁桥也会出现剧烈的 VIV 响应，但针对这些悬索桥截面几何形状的系统性研究却较少。此外，对于这种类型的桥梁，很少对非结构附加物（栏杆、屏风、整流罩）进行空气动力学优化。因此，我们对非流线型箱梁断面模型（受俄罗斯伏尔加格勒大桥启发）进行了风洞研究，该模型配备了两种类型的交通护栏，护栏高度与桥面宽度之比较大。考虑了实际的攻角范围（从 -3° 到 3°），并测量了静力、气动弹性振动和尾流速度波动。结果发现，振动振幅和锁定曲线模式的变化很大，甚至出乎意料，这说明可能存在相互竞争的激励机制。事实上，低孔隙率障碍物会改变涡流脱落的特性，特别是在甲板上部形成空腔，而众所周知，空腔会促进冲击剪切层不稳定性，就像在 H 型断面中一样。这种涡流脱落机制可能与卡尔曼涡流脱落同时存在，与静态试验中根据斯特劳哈尔数测得的预测结果相比，它可能是导致 VIV 发生时间大大提前的原因。次要激励机制的强度及其与主要机制的相互作用在很大程度上取决于攻角，并在很大程度上导致了 VIV 桥响应在定性模式和峰值振幅方面的深刻变化。在某些情况下，这些相互竞争的涡流曳引机制的轨迹甚至在测试桥梁模型的 VIV 响应曲线中清晰可见。最后，还根据准稳态理论对风洞结果进行了重新考虑，突出了一些甚至是定性的差异。

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引用次数: 0

Nonlinear aeroelastic behavior of a two-dimensional heated panel by irregular shock reflection considering viscoelastic damping 考虑粘弹性阻尼的二维加热板在不规则冲击反射作用下的非线性气动弹性行为

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-25 DOI: 10.1016/j.jfluidstructs.2024.104230

Yiwen He , Aiming Shi , Earl H. Dowell , Shengxi Zhou

This paper investigates the aeroelastic stability and nonlinear aeroelastic behavior of a two-dimensional heated panel in irregular shock reflection and extends prior work to include the effects of viscoelasticity. The aeroelastic model is formulated using the von Kármán large deflection plate theory and the Kelvin–Voigt damping model, accompanied by the quasi-steady thermal stress theory. The unsteady aerodynamic pressure is evaluated through the piston theory and the compressibility-corrected potential theory. The Galerkin approach is used to discretize the governing equation. The Lyapunov indirect method is applied to conduct theoretical analysis, obtaining the aeroelastic stability boundary. Also, the nonlinear aeroelastic response is numerically simulated via the fourth-order Runge–Kutta method. The proper orthogonal decomposition is applied to the panel deflection to manifest the influence of various system parameters. It is demonstrated that the shock wave aggravates the aerodynamic heating, lowering the critical buckling temperature. The viscoelastic damping restricts the impact of shock impingement location and shock strength on the stability boundary and also transforms the chaotic motions into periodic LCOs.

本文研究了二维加热板在不规则冲击反射下的气动弹性稳定性和非线性气动弹性行为，并扩展了之前的工作，将粘弹性的影响纳入其中。气动弹性模型是利用 von Kármán 大挠度板理论和 Kelvin-Voigt 阻尼模型以及准稳定热应力理论建立的。非稳定气动压力通过活塞理论和可压缩性校正势理论进行评估。伽勒金方法用于对控制方程进行离散化。应用 Lyapunov 间接法进行理论分析，获得气动弹性稳定边界。同时，通过四阶 Runge-Kutta 方法对非线性气动弹性响应进行数值模拟。对面板挠度进行适当的正交分解，以体现各种系统参数的影响。结果表明，冲击波加剧了空气动力加热，降低了临界屈曲温度。粘弹性阻尼限制了冲击撞击位置和冲击强度对稳定边界的影响，并将混沌运动转化为周期性 LCO。

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引用次数: 0

Estimation of wind force time-history using limited floor acceleration responses by modal analysis 通过模态分析利用有限楼层加速度响应估算风力时程

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-22 DOI: 10.1016/j.jfluidstructs.2024.104203

Daiki Sato , Razelle Dennise A. Soriano , Alex Shegay , Kou Miyamoto , Jinhua She , Kazuhiko Kasai

Time-history analyses are usually performed to design and examine the performance of tall structures subjected to strong wind loading. An accurate estimate of the time history of wind forces is required to carry out time-history analysis. However, previous studies conducted to estimate the time-history of wind forces require a lot of priori information, such as complete structural parameters and wind-induced responses, which are generally not available in actual conditions. This work addresses the estimation of the time-history of wind forces acting on each story of a ten degree-of-freedom model under the assumption that only the mass and acceleration responses measured on three stories are known. First, cubic spline interpolation is used to determine the unknown acceleration responses and frequency domain integration is used to obtain the velocity and displacement responses. Then, unknown structural parameters (particularly stiffness and damping) are estimated by the Frequency Domain Decomposition method. Finally, the obtained responses and structural parameters are used to estimate the wind forces using the equation of motion. It is demonstrated that the proposed methodology can accurately estimate the input wind forces on the structure.

时程分析通常用于设计和检查承受强风荷载的高层建筑结构的性能。要进行时间历程分析，就必须准确估算风力的时间历程。然而，以往估算风力时间历程的研究需要大量先验信息，如完整的结构参数和风致响应，而这些信息在实际条件下通常无法获得。本研究在只知道三层楼测得的质量和加速度响应的假设条件下，估算了作用在十自由度模型每一层楼上的风力的时间历程。首先，使用三次样条插值法确定未知加速度响应，并使用频域积分法获得速度和位移响应。然后，利用频域分解法估算未知结构参数（尤其是刚度和阻尼）。最后，利用获得的响应和结构参数，利用运动方程估算风力。结果表明，所提出的方法可以准确估算出结构上的输入风力。

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引用次数: 0

Mode split prediction for rotating disks with flexible stator coupling 具有柔性定子耦合的旋转盘的模式分裂预测

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-22 DOI: 10.1016/j.jfluidstructs.2024.104224

Lucas Berthet , Philippe Blais , Bernd Nennemann , Christine Monette , Frederick P. Gosselin

High-head turbine runners are subject to multiple sources of excitation. Coupled with the added mass of water, rotation induces a mode split in the natural frequencies of runners, where co-rotating and counter-rotating waves travel through the runner at different relative speeds. Disks, by displaying a similar behavior, can be used as a geometrically simpler model. Mode split is characterized for a rotating disk in dense fluid but, in high-head turbines, the runner and the compliant confinement are coupled through the axial gap fluid. In this article, we develop an analytical model of coupled stationary and rotating disks to analyze the effect of their interaction on the mode split phenomenon. First, we apply the potential flow theory, considering the fluid as irrotational, inviscid and incompressible. We assume that the modeshapes of the disk in a dense fluid are similar to their shapes in vacuum. We then derive the potential flows that respect the no-penetration boundary conditions. One after the other, each disk is considered flexible while the other one is rigid. By applying the superposition principle, we then couple the two obtained fluid flows through the structural equations of motion. A finite-element vibro-acoustic modal analysis was developed to verify the analytical model and propose a fast numerical tool for hydraulic turbine design. Analytical results show that rotation induces a split of the coupled rotor–stator frequencies as for a lone rotor, while the ratio of their amplitudes varies slightly. A change in the relative thickness of the rotor and stator affects their individual frequencies in vacuum, and in turn their coupling by the fluid, with a potential shift in dominance.

高水头水轮机转轮受到多种激励源的影响。加上水的附加质量，旋转会导致转轮固有频率的模式分裂，其中同向旋转波和反向旋转波以不同的相对速度穿过转轮。圆盘具有类似的行为，可用作几何上更简单的模型。稠密流体中的旋转圆盘具有模态分裂特征，但在高水头涡轮机中，转轮和顺应性约束通过轴向间隙流体耦合。在本文中，我们建立了一个耦合静止盘和旋转盘的分析模型，以分析它们之间的相互作用对模式分裂现象的影响。首先，我们应用势流理论，将流体视为非旋转、不粘性和不可压缩流体。我们假设圆盘在稠密流体中的模态形状与它们在真空中的形状相似。然后，我们推导出遵守无渗透边界条件的势流。每个圆盘都被认为是柔性的，而另一个圆盘则是刚性的。应用叠加原理，我们通过结构运动方程将两个得到的流体流耦合起来。为了验证分析模型，我们开发了有限元振动-声学模态分析，并为水轮机设计提供了一种快速的数值工具。分析结果表明，旋转会导致转子-定子耦合频率的分裂，与单独转子的情况相同，但其振幅比略有不同。转子和定子相对厚度的变化会影响它们在真空中的各自频率，进而影响它们在流体中的耦合，并可能改变主导地位。

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引用次数: 0

Fluid-structure interaction analysis of an elastic surface-piercing propellers 弹性表面穿孔螺旋桨的流固耦合分析

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-21 DOI: 10.1016/j.jfluidstructs.2024.104228

M Pakian Bushehri , MR Golbahar Haghighi , P Malekzadeh , E Bahmyari

In high-speed planing craft, surface-piercing propellers (SPPs) operate semi-submerged in a two-phase air-water environment, facing stress and displacement from variable forces. In this paper, the fluid-structure interaction (FSI) of the SPP is investigated at immersion ratios of 30 %, 50 %, 70 % and 90 %, under low and high advance coefficients. A coupling of Reynolds-averaged Navier–Stokes equations (RANS) and elasticity theory are used to simulate fluid dynamics and the blade deformation with the multi-physics computational fluid dynamics software STAR-CCM+. The analysis is performed after several rotations of the SPPs at five different positions. The results show that at the advance coefficient of 0.4, a higher immersion ratio increases torque, thrust, efficiency, maximum stress, and maximum displacement. When the advance coefficient is equal to one, the efficiency, maximum stress, and maximum displacement remain constant for the immersion ratio above 50 %. The maximum displacement occurs at the blade tip, while maximum stress is at the trailing edge root. Most blade deformations happen where the blade enters the water, aligns perpendicularly with the water surface, and exits. The two-phase flow around the blade increases its displacement.

在高速刨削艇中，表面推进器（SPP）半浸没在空气-水两相环境中运行，面临着来自可变力的应力和位移。本文研究了 SPP 在浸入比为 30%、50%、70% 和 90% 时，在低和高推进系数下的流固耦合（FSI）问题。使用多物理场计算流体动力学软件 STAR-CCM+，将雷诺平均纳维-斯托克斯方程（RANS）和弹性理论耦合，模拟流体动力学和叶片变形。在 SPP 于五个不同位置旋转数次后进行分析。结果表明，当推进系数为 0.4 时，较高的浸入比会增加扭矩、推力、效率、最大应力和最大位移。当超前系数等于 1 时，浸入比超过 50 % 时，效率、最大应力和最大位移保持不变。最大位移出现在叶尖，而最大应力则出现在后缘根部。大多数叶片变形发生在叶片进入水中、与水面垂直并离开水面的地方。叶片周围的两相流增加了叶片的位移。

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引用次数: 0

Unsteady load mitigation through passive pitch 通过被动俯仰减轻不稳定载荷

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-21 DOI: 10.1016/j.jfluidstructs.2024.104216

Yabin Liu , Riccardo Broglia , Anna M. Young , Edward D. McCarthy , Ignazio Maria Viola

Mitigation of load fluctuations due to flow unsteadiness is critical in a broad range of applications, including wind/tidal turbines, and aerial/underwater vehicles. While the use of active control systems is an established practice in engineering, passive systems are not well understood, and the limits of their efficacy are yet to be ascertained. To this end, the present study aims to provide new insights into the effectiveness of passive pitching in the mitigation of lift fluctuations in the most demanding case of fast, high-amplitude variations of the free stream speed and direction. We perform fluid-structure interaction simulations of a two-dimensional free-to-pitch rigid foil. Our study reveals that the lift amplitude of the force fluctuations can be decreased by at least two-thirds through passive pitching. The efficacy of the unsteady load mitigation is only weakly dependent on the exact pitching axis location, and the optimal position is upstream and close to the axis of the foil. These results may inform the design of passive control systems of wind/tidal turbines and aerial/underwater vehicles and provide new insights into interpreting the control strategy of natural flyers such as insects and birds.

在包括风力/潮汐涡轮机和航空/水下航行器在内的多种应用中，减缓因流动不稳定性引起的负载波动至关重要。虽然使用主动控制系统是工程领域的惯例，但人们对被动系统的了解并不多，其功效的局限性也有待确定。为此，本研究旨在对被动俯仰系统在自由流速度和方向快速、高振幅变化的最苛刻情况下减缓升力波动的有效性提供新的见解。我们对二维自由俯仰刚性箔片进行了流固耦合模拟。我们的研究表明，通过被动俯仰，力波动的升力振幅至少可以降低三分之二。减轻非稳定载荷的效果只与俯仰轴的具体位置有微弱的关系，最佳位置在箔片轴线的上游和附近。这些结果可为风力/潮汐涡轮机和空中/水下飞行器被动控制系统的设计提供参考，并为解读昆虫和鸟类等自然飞行器的控制策略提供新的见解。

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引用次数: 0

Numerical investigation of fluid–structure interaction in a pilot-operated microfluidic valve 先导微流控阀门中流体与结构相互作用的数值研究

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-21 DOI: 10.1016/j.jfluidstructs.2024.104226

Ahmed Aissa-Berraies , E. Harald van Brummelen , Ferdinando Auricchio

The present paper is concerned with numerical investigation of the performance of a pilot-operated control valve based on shape memory alloy actuation control. The valve under investigation can be integrated into miniaturized hydraulic systems and is developed to perform precise dispensing, mixing, or dosing tasks while being able to withstand relatively high pressure differences. The study evaluates the valve’s response under the current ON/OFF and the desired proportional control regimes using numerical methods for fluid–structure interaction. The computational model replicates the operation of the valve, which requires an understanding of the complex interactions between the fluid flow with the pressurized valve and the contact with the valve seat during the opening and closing processes. In addition, the model leverages advanced numerical techniques to overcome several complexities arising mainly from the geometrical, material, and contact nonlinearities, and to mitigate the shortcomings of the partitioned fluid–structure interaction approach. Several 3D fluid–structure-contact-interaction simulations are conducted to examine the valve’s structural and flow behavior under varying pressure conditions. Results indicate that the valve is adequate for ON/OFF actuation control but is susceptible to flow-induced vibrations during the proportional control regime that occurs due to the sharp pressure drop in the valve-seat gap and the ensuing Venturi effect, which counteract the opening of the main valve. The fluid–structure-interaction simulations provide insight into the mechanism underlying the flow-induced vibrations, which can serve to improve the design and enhance the performance of the valve in microfluidic applications.

本文对基于形状记忆合金执行控制的先导控制阀的性能进行了数值研究。所研究的阀门可集成到微型液压系统中，用于执行精确的分配、混合或配料任务，同时能够承受相对较高的压力差。这项研究采用流体与结构相互作用的数值方法，评估了阀门在当前开/关和所需比例控制状态下的响应。计算模型复制了阀门的运行过程，这就要求了解在打开和关闭过程中，流体流动与受压阀门以及与阀座接触之间复杂的相互作用。此外，该模型还利用先进的数值技术克服了主要由几何、材料和接触非线性引起的若干复杂问题，并减轻了分区流固耦合方法的缺点。我们进行了多次三维流体-结构-接触-相互作用模拟，以检查阀门在不同压力条件下的结构和流动行为。结果表明，该阀门适用于 ON/OFF 驱动控制，但在比例控制状态下，由于阀座间隙中的急剧压降和随之产生的文丘里效应（Venturi effect）会抵消主阀的开启，因此容易发生由流动引起的振动。流体-结构-相互作用模拟深入揭示了流动诱发振动的机理，有助于改进微流控应用中阀门的设计并提高其性能。

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引用次数: 0

Flow-induced buckling of a bistable beam in uniform flow 均流中双稳态梁的流动诱导屈曲

IF 3.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Journal of Fluids and Structures

Pub Date : 2024-11-20 DOI: 10.1016/j.jfluidstructs.2024.104220

Leixin Ma , Wenyu Chen , Ruosi Zha , Alejandra Hernandez Escobar

Recent developments in soft materials enable the design and manufacturing of bistable flexible structures. Their fast snap-through buckling mechanisms have been utilized to introduce fast locomotion. In this paper, we aim to understand the impact of fluid–structure interaction (FSI) on the dynamics of bistable structures. We report the numerical analysis of the snap-through buckling phenomena for several bistable flexible structures fixed at both ends. The motion is driven by the fluid loading of different flow speeds. The large deformation of the bistable structure is coupled with the incoming fluid flow via the Arbitrary Lagrangian–Eulerian (ALE) method. During the snap-through buckling process, the corresponding structural deformation patterns, hydrodynamic force distributions, and fluid patterns are discussed. Larger steady-state deformation is found for the bistable structure, compared to its mono-stable counterpart in the same flow condition. The Cauchy number is found to be the critical parameter affecting the buckling dynamics and dimensionless strain energy stored in the system. A prediction model for the dimensionless strain energy as a function of the Cauchy number is proposed. The hydrodynamic lift force generated by the fluid is found to increase the total strain energy of these bistable structures. The research could provide insight in designing morphable marine energy devices and lightweight bioinspired propulsion systems.

软材料的最新发展使得双稳态柔性结构的设计和制造成为可能。双稳态柔性结构的快速屈曲机制已被用于引入快速运动。本文旨在了解流固耦合（FSI）对双稳态结构动力学的影响。我们报告了对几种两端固定的双稳态柔性结构的扣穿屈曲现象的数值分析。运动由不同流速的流体负载驱动。双稳态结构的大变形通过任意拉格朗日-欧拉（ALE）方法与流入的流体流耦合。讨论了在快穿屈曲过程中，相应的结构变形模式、流体动力分布和流体模式。发现在相同的流动条件下，双稳态结构的稳态变形比单稳态结构更大。研究发现，考奇数是影响屈曲动力学和系统中存储的无量纲应变能的关键参数。提出了一个无量纲应变能与考奇数函数关系的预测模型。研究发现，流体产生的流体动力升力会增加这些双稳态结构的总应变能。这项研究可为设计可变形海洋能源装置和轻质生物启发推进系统提供启示。

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