European Journal of Mechanics B-fluids最新文献

Study on the energy dissipation mechanism of three-degree-of-freedom acoustic vibration system due to high-viscosity fluid motion 高粘度流体运动下三自由度声振动系统能量耗散机理研究

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-19 DOI: 10.1016/j.euromechflu.2026.204473

Lei Yu, Xiaobin Zhan, Tielin Shi

This paper is aimed to study the energy dissipation mechanism of the three-degree-of-freedom (three-DOF) acoustic vibration system due to high-viscosity fluid motion. A simulation model describing the dynamic interaction between a three-DOF acoustic vibration system and the fluid is established using computational fluid dynamics (CFD) and fluid-structure interaction (FSI) methods. The simulation results show that under acoustic vibration excitation, the fluid inside the vessel rapidly transitions from a relatively stationary state to violent motion behavior. The key factor in the energy dissipation of the fluid is caused by the phase difference between the fluid force as the fluid impacts on the wall and the motion imposed on the vessel. The energy input to the system is primarily dissipated by the fluid and the structural damping of the system. The effects of excitation amplitude, excitation frequency, filling ratio, and fluid viscosity on the energy dissipation of the system are also analyzed in this study. An increase in the excitation amplitude as well as an increase in the excitation frequency within a certain frequency range, results in an enhancement of the systems' dynamic response, which leads to a significant increase in the energy input to the system and the energy dissipated by the fluid. In the range of filling ratios investigated in this study, the total input energy and fluid dissipation energy are minimized at the filling ratio of 50 %. Furthermore, an increase in fluid viscosity results in higher fluid energy dissipation and input energy.

本文旨在研究高粘度流体运动下三自由度声振动系统的能量耗散机理。采用计算流体力学（CFD）和流固耦合（FSI）方法，建立了描述三自由度声振动系统与流体动力学相互作用的仿真模型。仿真结果表明，在声振动激励下，容器内流体由相对静止状态迅速转变为剧烈运动状态。影响流体能量耗散的关键因素是流体冲击壁面时流体力与施加在容器上的运动之间的相位差。输入系统的能量主要由流体和系统的结构阻尼耗散。分析了激励幅值、激励频率、填充比和流体粘度对系统能量耗散的影响。在一定频率范围内，随着激励幅值的增加和激励频率的增加，系统的动态响应会增强，从而导致系统输入的能量和流体耗散的能量显著增加。在本研究所研究的填充比范围内，当填充比为50% %时，总输入能量和流体耗散能量最小。此外，流体粘度的增加导致流体能量耗散和输入能量的增加。

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引用次数: 0

A convective instability analysis of a channel flow within a saturated porous medium 饱和多孔介质中通道流动的对流不稳定性分析

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-23 DOI: 10.1016/j.euromechflu.2026.204474

V. Kandavelu , L. Tlau , P.T. Griffiths

The influence of convection in a horizontal channel filled with a porous medium is examined to assess the stability of the fluid flow between the two walls that are held fixed at different temperatures. The flow is described by the Navier–Stokes equations, while heat transfer is captured through the energy equation. A coupled linear stability system is derived and solved using a Chebyshev spectral collocation method. The study focuses on the impact of the relevant nondimensional parameters on the development of the perturbations and the onset of instability within the flow. The onset of convection is advanced as the porous parameter

(M)

increases, while higher Prandtl numbers

(P r)

and Reynolds numbers

(R e)

delay the onset of convection. The growth rate is unaffected by increases in

P r

and the Rayleigh number

(R a)

; however, it increases as

M

decreases and as

R e

increases. The isocontours show that increasing

P r

stabilizes temperature variations in the inner flow region.

研究了在充满多孔介质的水平通道中对流的影响，以评估在不同温度下固定的两面墙之间流体流动的稳定性。流动由Navier-Stokes方程描述，而传热通过能量方程捕获。推导了一个耦合线性稳定系统，并采用切比雪夫谱配置法求解。研究了流动中相关的无量纲参数对扰动发展和不稳定发生的影响。随着孔隙参数(M)的增大，对流的发生提前，而较高的普朗特数（Pr）和雷诺数（Re）会延迟对流的发生。生长速率不受Pr和瑞利数（Ra）增加的影响；而随着M的减小和Re的增大，它增大。等等值线表明，Pr的增加使内流区的温度变化趋于稳定。

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引用次数: 0

Parallel Social Group Optimization for physics-informed calibration of RANS turbulence models: Accuracy, robustness, and generalization 平行社会群体优化的物理通知RANS湍流模型的校准：准确性，稳健性和泛化

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-02-05 DOI: 10.1016/j.euromechflu.2026.204486

Amar Singh , Vinod Kumar Shukla , Sukanta Ghosh

We present Parallel Social Group Optimization (PSGO) for physics-informed calibration of eddy-viscosity RANS closures, with a practical focus on separated, wall-bounded flows where, prediction hinges on accurate separation and reattachment. The method is derivative-free and HPC-friendly: multiple social groups evaluate independent RANS jobs in parallel while four staged operators (self-learning, improving, acquiring, combining) balance exploration and contraction. We first benchmark PSGO on continuous black-box test functions to validate optimizer reliability, then apply it to tune the coefficients of the SST k–ω model using a multi-case objective built from periodic hill and canonical wall-bounded flows. Under matched budgets, PSGO shows faster median convergence and lower run-to-run variability than GA/PSO/DE/CS (coefficient of variation 0.17 vs GA 0.41, PSO 0.36). Using the calibrated coefficients without re-tuning, we assess in-family transfer on an unseen backward-facing step at a single Reynolds number: the reattachment length improves from 7.2 h (baseline) to 6.3 h, close to DNS (6.0 h), and mean-velocity/pressure profiles are consistently closer to reference. The scope of this study is application-specific, eddy-viscosity RANS calibration for separation–reattachment flows at moderate Reynolds numbers; cross-physics and multi-Re robustness are outlined as future work.

我们提出了平行社会群体优化（PSGO），用于涡流粘度RANS闭包的物理信息校准，其实际重点是分离的、有壁的流动，其中预测取决于准确的分离和再附着。该方法无衍生，且对hpc友好：多个社会团体并行评估独立的RANS作业，而四个阶段的操作（自我学习、改进、获取、组合）平衡探索和收缩。我们首先在连续黑盒测试函数上对PSGO进行基准测试，以验证优化器的可靠性，然后使用由周期性山丘流和典型壁界流构建的多情况目标将其应用于调整SST k -ω模型的系数。在匹配预算下，PSGO比GA/PSO/DE/CS表现出更快的中位数收敛和更低的运行间变异性（变异系数0.17 vs GA 0.41, PSO 0.36）。使用未重新调整的校准系数，我们在单个雷诺数下对未见过的向后步骤进行了家族内转移评估：再附着长度从7.2 h（基线）提高到6.3 h，接近DNS(6.0 h)，平均速度/压力剖面始终更接近参考。本研究的范围是应用特定的，涡流粘度RANS校准分离-再附着流在中等雷诺数；跨物理和多re鲁棒性概述了未来的工作。

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引用次数: 0

Visualising coherent vortices generated by a swimming dolphin 正在观察游泳的海豚所产生的连贯漩涡

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-07 DOI: 10.1016/j.euromechflu.2025.204452

Yutaro Motoori, Hideki Murahata, Susumu Goto

We visualise the hierarchy of coherent vortices generated by a freely swimming dolphin, obtained from direct numerical simulations at a high Reynolds number. The visualisations are based on isosurfaces of the second invariant of the velocity gradient tensor evaluated from scale-decomposed velocity fields. We describe in detail the scale-decomposition procedure and the polygon-based visualisation, which enables the rendering of the data despite their large size. We also emphasise that visualising the hierarchy of coherent vortices clarifies the physical mechanism of dolphin propulsion, and more generally, provides physical insight into turbulence around swimming and flying organisms.

在高雷诺数的直接数值模拟中，我们可视化了自由游泳的海豚产生的相干涡的层次结构。可视化是基于速度梯度张量的第二不变量的等值面，从尺度分解的速度场中评估。我们详细描述了尺度分解过程和基于多边形的可视化，这使得数据的渲染，尽管他们的大尺寸。我们还强调，可视化连贯漩涡的层次结构阐明了海豚推进的物理机制，更广泛地说，提供了对游泳和飞行生物周围湍流的物理见解。

引用次数: 0

Yarn dynamics in a pneumatic guiding tube: Numerical simulation and experimental validation 气动导向管内纱线动力学：数值模拟与实验验证

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-16 DOI: 10.1016/j.euromechflu.2026.204464

Tianbo Liu, Qitao Huang, Yuliang Yan, Tianyi Wang, Jiahui Wang, Hongguang Xu

The yarn in the pneumatic guiding tube has high fineness and considerable flexibility. As a result, it undergoes complex deformations under the airflow, making the fluid–structure interaction (FSI) between the yarn and airflow difficult to simulate. This study develops a weakly coupled numerical simulation framework to address this issue. The airflow and the fine yarn are modeled separately. The flow velocity is obtained using an upstream sampling method and applied to the yarn model. The yarn dynamics model is advanced using the implicit method. After updating the yarn position, the flow field is updated via force projection, thereby realizing a two-way FSI simulation. The kinematic and dynamic characteristics of yarn under pneumatic guiding tube control are systematically investigated through the framework. In yarn conveying process, the yarn quality flow stability and distribution concentration are found to increase first and then decrease with the increase of the input flow velocity. For the yarn tensioning process, the tension and vibration of the yarn continuously increase as the input velocity rises. The simulation framework is validated through experimental comparisons. Based on the simulation results and experimental data, the allowable ranges and optimal intervals of input velocity under different operating conditions are determined.

导纱管内的纱线细度高，柔韧性好。因此，纱线在气流作用下会发生复杂的变形，使得纱线与气流之间的流固耦合（FSI）难以模拟。本研究开发了一个弱耦合数值模拟框架来解决这个问题。气流和细纱分别建模。采用上游采样法得到了纱线的流速，并将其应用于纱线模型。采用隐式方法建立了纱线动力学模型。更新纱线位置后，通过力投射更新流场，从而实现双向FSI仿真。通过该框架系统地研究了气动导管控制下纱线的运动学和动力学特性。在纱线输送过程中，随着输入流速的增大，纱线质量、流动稳定性和分布浓度先增大后减小。在纱线张紧过程中，随着输入速度的增加，纱线的张力和振动不断增大。通过实验对比验证了仿真框架的有效性。根据仿真结果和实验数据，确定了不同工况下输入速度的允许范围和最优区间。

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引用次数: 0

Nonlinear dynamics of dust-acoustic waves in cometary plasmas: Supernonlinear periodic waves, charge asymmetry, and thermal gradients bridging astrophysical and industrial applications 彗星等离子体中尘埃声波的非线性动力学：超非线性周期波、电荷不对称和热梯度，连接天体物理和工业应用

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-17 DOI: 10.1016/j.euromechflu.2026.204469

M.A. El-Borie , Reem Altuijri , Abdel-Haleem Abdel-Aty , A. Atteya , Pralay Kumar Karmakar , Kottakkaran Sooppy Nisar , Nadia Alsaeed Saad

This work investigates the behavior of dust-acoustic waves (DAWs) in cometary plasmas including opposite-polarity dust grains, Maxwellian ions, and suprathermal electrons. We derived the modified Korteweg–de Vries (mKdV) equation to define periodic, superperiodic, and solitary wave solutions. Bifurcation analysis uncovers supernonlinear periodic waves (SPOs), a novel class of coherent structures sustained under extreme nonlinearity through precise nonlinear-dispersive balance. The phase velocity of DAWs is shown to rise with increasing positive-to-negative dust charge ratio,

α_{d}

, and negative-to-positive dust temperature ratio,

δ_{1}

, while nonlinear coefficients decline, contrasting the dispersive term’s enhancement. Sagdeev potential analysis reveals dual energy minima governing compressive/rarefactive solitary waves, with thermal gradients

δ_{1}

modulating amplitude and width. Numerical simulations, benchmarked against laboratory parameters, demonstrate that heightened thermal contrast amplifies nonlinear coupling, driving larger-amplitude periodic waves. SPOs, distinguished by concentrated energy and potential turbulence onset, highlight efficient energy transport mechanisms critical to astrophysical plasmas. These findings advance predictive models for wave behavior in cometary tails, planetary rings, and laboratory experiments, offering insights into energy transfer, instability thresholds, and applications in space physics and industrial plasmas. The study bridges theoretical and observational gaps, underscoring the role of dust charge asymmetry and thermal gradients in shaping nonlinear wave dynamics.

这项工作研究了彗星等离子体中尘埃声波（DAWs）的行为，包括极性相反的尘埃颗粒、麦克斯韦离子和超热电子。我们推导了修正的Korteweg-de Vries （mKdV）方程来定义周期、超周期和孤立波解。分岔分析揭示了超非线性周期波（SPOs），这是一类通过精确的非线性色散平衡维持在极端非线性下的新型相干结构。随着正负粉尘电荷比αd和正负粉尘温度比δ1的增大，DAWs的相速度增大，而非线性系数减小，与色散项的增强形成对比。Sagdeev势分析表明，压缩/稀薄孤立波具有双能量最小值，热梯度δ1调节振幅和宽度。以实验室参数为基准的数值模拟表明，增强的热对比放大了非线性耦合，驱动了更大幅度的周期波。spo以集中的能量和潜在的湍流起始为特征，强调了对天体物理等离子体至关重要的有效能量传输机制。这些发现推进了彗星尾巴、行星环和实验室实验中波动行为的预测模型，为能量转移、不稳定阈值以及空间物理和工业等离子体的应用提供了见解。该研究弥补了理论和观测的空白，强调了尘埃电荷不对称和热梯度在形成非线性波动动力学中的作用。

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引用次数: 0

A kinetic scheme based on positivity preservation for multi-component Euler equations 基于正守恒的多组分欧拉方程动力学格式

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-02-14 DOI: 10.1016/j.euromechflu.2026.204490

Shashi Shekhar Roy, S.V. Raghurama Rao

A kinetic model with flexible velocities is presented for solving the multi-component Euler equations. The model employs a two-velocity formulation in 1D and a three-velocity formulation in 2D. In 2D, the velocities are aligned with the cell-interface to ensure a locally one-dimensional macroscopic normal flux in a finite volume. The velocity magnitudes are defined to satisfy conditions for preservation of positivity of density of each component as well as of overall pressure for first order accuracy under a CFL-like time-step restriction. Additionally, at a stationary contact discontinuity, the velocity definition is modified to achieve exact capture. The basic scheme is extended to third order accuracy using a Chakravarthy-Osher type flux-limited approach along with three-stage, third-order Strong Stability Preserving Runge–Kutta (SSPRK) method. Benchmark 1D and 2D test cases, including shock-bubble interaction problems, are solved to demonstrate the efficacy of the solver in accurately capturing the relevant flow features.

提出了求解多分量欧拉方程的柔性速度动力学模型。该模型采用一维双速度公式和二维三速度公式。在二维中，速度与细胞界面对齐，以确保有限体积内的局部一维宏观法向通量。速度大小的定义是为了满足在类似cfl的时间步长限制下，保持各组分密度的正性和总压力的一阶精度的条件。此外，在静止接触不连续时，修改速度定义以实现精确捕获。利用chakravarty - osher型通量限制方法和三段式三阶强保稳龙格-库塔（SSPRK）方法将基本方案扩展到三阶精度。对基准一维和二维测试用例进行了求解，包括激波-气泡相互作用问题，以证明求解器在准确捕获相关流动特征方面的有效性。

引用次数: 0

Linear and nonlinear stability analysis of thermotactic bioconvection 热致性生物对流的线性和非线性稳定性分析

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-27 DOI: 10.1016/j.euromechflu.2026.204481

Keshav Singh , Y.D. Sharma , Sanjalee Maheshwari

Thermotactic microorganisms are motile organisms that migrate in response to temperature gradients, exhibiting movement toward heat sources. Understanding thermotaxis is vital for advancements in biotechnology, wastewater treatment, and medical microbiology. In this study, the onset of bioconvection in a fluid layer containing thermotactic microorganisms is investigated through both linear and nonlinear stability analysis under free–free boundary conditions. The linear stability analysis is carried out by introducing infinitesimal perturbations and applying the normal mode technique, resulting in an eigenvalue problem. For the nonlinear analysis, an energy method is employed. A variational formulation is developed, which is further used to derive an eigenvalue problem. The obtained eigenvalue problems is finally solved using the Galerkin technique. A comparative study between the linear and nonlinear results is performed to highlight the differences in critical thresholds. The findings indicate that the Péclet number destabilizes the system, and as its value increases, the subcritical region of instability decreases. Furthermore, stronger thermal effects lead to an earlier onset of bioconvection, characterized by a reduction in the critical bioconvection Rayleigh number. These insights can aid in the practical design and control of bioconvective systems in bioengineering, environmental treatment processes, and industrial fluid technologies.

热致微生物是一种可移动的生物，它们根据温度梯度进行迁移，表现出向热源移动的特征。了解热致性对生物技术、废水处理和医学微生物学的进步至关重要。在本研究中，通过在自由-自由边界条件下的线性和非线性稳定性分析，研究了含热致微生物的流体层中生物对流的发生。通过引入无穷小摄动并应用正态模态技术进行线性稳定性分析，得到一个特征值问题。对于非线性分析，采用能量法。本文提出了一个变分公式，并利用该公式推导了一个特征值问题。最后利用伽辽金技术求解得到的特征值问题。在线性和非线性结果之间进行了比较研究，以突出临界阈值的差异。结果表明，passiclet数使系统失稳，且随着passiclet数的增大，亚临界区域的失稳减小。此外，更强的热效应导致生物对流开始时间提前，其特征是临界生物对流瑞利数降低。这些见解有助于生物工程、环境处理过程和工业流体技术中生物对流系统的实际设计和控制。

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引用次数: 0

Influence of slip-yield stress model on the oscillatory squeeze flow of a viscoelastic fluid confined between two spheres 滑移-屈服应力模型对两球间粘弹性流体振荡挤压流动的影响

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-13 DOI: 10.1016/j.euromechflu.2026.204466

D. Matuz , F. Méndez , J. Arcos , O. Bautista , R. Baños

In this study, we examine the oscillatory squeeze flow of a viscoelastic fluid confined between two hydrophobic spheres of differing radii. The fluid flow is generated by the harmonic motion of an upper sphere, while the lower sphere remains stationary. We have considered that the gap between the spheres is much smaller than their radii and that the oscillation amplitude of the moving sphere is small compared to this gap. Under these conditions, the curved surfaces can be approximated by quadratic functions of the radial coordinate

r

. A dynamic slip law is used to model slippage at the fluid–solid interface, which incorporates interfacial memory effects through the slip-relaxation time, together with the slip-yield Spikes–Granick condition, in which interfacial slippage arises when the fluid shear stress exceeds a critical value; otherwise, a non-slip region persists. Given the dominance of viscous over inertial effects, the convective terms in the momentum equation were neglected, and the analysis was carried out in a strictly periodic regimen. An analytical solution of the governing equations is derived, where the following parameters control the phenomenon: the Deborah number

De

, the Womersley number

α

, the Navier slip length

\tilde{λ}

, the slip relaxation number

{De}_{s}

and the critical shear stress at the fluid–solid interface

{\tilde{τ}}_{c}

. Our findings indicate that, relative to flat surfaces, when curved surfaces are assumed, the zone of the non-slip region decreases. Additionally, incorporating viscoelastic fluids results in a diminished compression force, and lower mechanical power is consumed by implementing hydrophobic surfaces, high oscillation frequencies, and viscoelastic fluids.

在这项研究中，我们研究了粘弹性流体在两个不同半径的疏水球体之间的振荡挤压流动。流体流动是由上球的调和运动产生的，而下球保持静止。我们已经考虑到球体之间的间隙比它们的半径小得多，并且与这个间隙相比，运动球体的振荡幅度很小。在这些条件下，曲面可以用径向坐标r的二次函数来近似。采用动态滑移定律来模拟流固界面的滑移，其中通过滑移松弛时间考虑了界面记忆效应，以及滑移屈服尖峰-格兰尼克条件，在该条件下，当流体剪切应力超过临界值时，界面发生滑移；否则，一个防滑区域将持续存在。考虑到粘性效应优于惯性效应，动量方程中的对流项被忽略，并在严格的周期方案中进行分析。导出了控制方程的解析解，其中以下参数控制该现象：Deborah数De、Womersley数α、Navier滑移长度λ λ、滑移松弛数Des和流固界面处的临界剪切应力τ τ c。我们的研究结果表明，相对于平面，当假设曲面时，防滑区区域减小。此外，粘弹性流体的加入减少了压缩力，并且通过疏水表面、高振荡频率和粘弹性流体消耗的机械功率更低。

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引用次数: 0

Influence of front airfoil leading-edge serrations on turbulence interaction noise characteristics of tandem airfoils at different angles of attack 前翼型前缘锯齿对不同迎角下串列翼型湍流相互作用噪声特性的影响

IF 2.5 3区工程技术 Q2 MECHANICS

European Journal of Mechanics B-fluids

Pub Date : 2026-07-01 Epub Date: 2026-01-08 DOI: 10.1016/j.euromechflu.2026.204463

Xishuai Yu, Jianxi Zhou, Yong Li

This study investigates the effectiveness of leading-edge serrations as a passive noise control strategy for tandem airfoils across different angles of attack. Far-field noise measurements indicate that applying leading-edge serrations to the front airfoil significantly reduces wake turbulence interaction noise at 5° and 10° angles of attack; however, the reduction effect weakens as the angle of attack increases. At an angle of attack of 17°, the leading-edge serrations no longer reduce the peak wake turbulence interaction noise. Furthermore, neither the application of leading-edge serrations nor changes in the airfoil angle of attack affect the noise directivity. Flow field analyses based on Particle Image Velocimetry (PIV) reveal that the serrated leading edge markedly attenuates turbulence and vortex shedding in the wake of the front airfoil. Notably, as the angle of attack increases, the influence of vortex shedding and vortex–solid interference between the front and rear airfoils on the overall noise decreases. The intensity of the front airfoil wake turbulence and the extent of its interaction with the rear airfoil are identified as the dominant factors governing the interaction noise in tandem airfoils. Therefore, the application of leading-edge serrations in tandem airfoils is recommended only for low angles of attack. These findings may offer practical guidance for noise reduction in airfoil arrays of rotating machinery, such as guide vane rows, fan blade rows, and turbine blade rows.

本研究探讨了前缘锯齿作为一种被动噪声控制策略的有效性跨不同迎角串联式翼型。远场噪声测量表明，应用前缘锯齿到前翼型显著降低尾迹湍流相互作用噪声在5°和10°攻角；随着攻角的增大，减振效果逐渐减弱。当迎角为17°时，前缘锯齿不再降低尾迹湍流相互作用噪声峰值。此外，前缘锯齿的应用和翼型迎角的变化都不会影响噪声指向性。基于粒子图像测速（PIV）的流场分析表明，锯齿状前缘可以显著减弱前翼型尾迹中的湍流和旋涡脱落。值得注意的是，随着迎角的增大，旋涡脱落和前后翼型之间的涡固干涉对整体噪声的影响减小。确定了前翼型尾迹湍流的强度及其与后翼型相互作用的程度是控制串列型相互作用噪声的主要因素。因此，前缘锯齿在串联翼型的应用是建议只有低攻角。这些发现可以为旋转机械翼型阵列的降噪提供实用的指导，例如导叶排、风扇叶片排和涡轮叶片排。

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引用次数: 0