{"title":"Generalized coupled thermoacoustic modes in annular combustors introduced by Helmholtz resonators","authors":"Liming Yin, Dong Yang","doi":"10.1016/j.jsv.2025.119231","DOIUrl":"10.1016/j.jsv.2025.119231","url":null,"abstract":"<div><div>The present work studies the impact of Helmholtz resonators (HRs) on the thermoacoustic instability in annular combustors. It has been known that annular combustors can see purely longitudinal thermoacoustic modes where the acoustic field involves only the modal component with circumferential wave number <span><math><mrow><mi>n</mi><mo>=</mo><mn>0</mn></mrow></math></span>, purely spinning modes where the acoustic field involves only one (clockwise or anti-clockwise) modal component with a particular circumferential wave number such as <span><math><mrow><mi>n</mi><mo>=</mo><mo>+</mo><mn>1</mn></mrow></math></span> or <span><math><mrow><mo>−</mo><mn>1</mn></mrow></math></span>, standing or mixed modes where both the clockwise and anti-clockwise modal components of a given circumferential wave number coexist (such as <span><math><mrow><mi>n</mi><mo>=</mo><mo>±</mo><mn>1</mn></mrow></math></span>), and slanted modes where the acoustic field involves all three modal components with <span><math><mrow><mi>n</mi><mo>=</mo><mn>0</mn><mo>,</mo><mspace></mspace><mo>±</mo><mn>1</mn></mrow></math></span>. By employing both a 2D low-order network model and a 3D Helmholtz solver, we show for the first time that a type of generalized coupled thermoacoustic modes could result due to the presence of an HR. This type of modes could involve the coupling of even more circumferential modal components than that of the slanted modes. We first use an analytical model for an infinitely long annular duct to illustrate how the resonator’s characteristics, such as its inlet cross-sectional area and impedance, influence the acoustic modal coupling. An annular duct with finite length is then used to show that modes with this more general modal coupling can result due to the presence of an HR. We also confirm the HR’s bias flow Mach number and cavity volume as pivotal parameters in achieving exceptional points (EPs), where two acoustic modes merge. We show that, in the considered cases, the EPs are usually generalized coupled thermoacoustic modes. Further study considering the geometry of the MICCA combustor from the EM2C laboratory corroborates our findings, illustrating the HR’s capability in introducing the generalized coupled thermoacoustic modes in annular combustors, and the dependence of the EPs with different HR parameters. This investigation enhances understanding of HR-induced modal coupling, providing insights for designing acoustic dampers for advanced gas turbine combustors.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119231"},"PeriodicalIF":4.3,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Le Bras , K. Kucukcoskun , D. Acevedo-Giraldo , M. Roger
{"title":"Aeroacoustic simulations of two co-rotating propellers at low Reynolds number with installation effects","authors":"S. Le Bras , K. Kucukcoskun , D. Acevedo-Giraldo , M. Roger","doi":"10.1016/j.jsv.2025.119248","DOIUrl":"10.1016/j.jsv.2025.119248","url":null,"abstract":"<div><div>In this study, the sound radiated by two co-rotating propellers mounted side-by-side in close proximity is investigated numerically under low Reynolds number conditions. The pylon-mounted propellers, previously studied experimentally in the literature, are representative of the propellers equipping distributed electric propulsion architectures for aircraft. They consist of six-blade XPROP-S propellers operating at a rotational speed of 7000 rpm with constant pitch angle. Operating conditions at zero advance ratio are considered. The numerical simulations are carried out using a two-step hybrid approach. In the first step, an incompressible large-eddy simulation is performed to compute the flow field. In the second step, tonal and broadband noise predictions with installation effects are obtained using a high-order finite-element approach. The performance of the numerical approach is first verified for a single pylon-mounted propeller. The numerical methodology is then applied to the two-propeller configuration. Acoustic results are successfully compared to experimental data from the literature and further insights into the sound generation mechanisms are provided. In particular, for this zero-advance-ratio propeller configuration, the importance of accounting for propeller–propeller aerodynamic interactions to obtain accurate noise predictions is highlighted. Including installation effects in the acoustic simulations is also found to improve the predictions in the low frequency range.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119248"},"PeriodicalIF":4.3,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Lateral-torsional coupled vibration analysis of a dual-rotor system with bolted joint structure considering stick-slip behavior at mating interface","authors":"Zhimin Zhu , Yuqi Li , Yuanzhao Chen , Dingguo Zhang","doi":"10.1016/j.jsv.2025.119254","DOIUrl":"10.1016/j.jsv.2025.119254","url":null,"abstract":"<div><div>Interface stick-slip behavior will be induced for the assembly system during the long-term and complex vibration environment, further inducing strong nonlinear stiffness and damping. For this reason, the present work established a dynamic model of the bolted joint dual-rotor system considering interface stick-slip behavior and conducted a parametric analysis of the effect of the preload and speed ratios on the system’s lateral-torsional coupled vibration performance. Wherein the interface stick-slip behavior is simulated by adopting the Iwan model, and the equations of motions of the dual-rotor system, including the low-pressure (LP) and high-pressure (HP) rotors, are established based on the lumped mass method. The results indicate that both the preload and speed ratio have a significant effect on the variation of equivalent average stiffness of the bolted joint induced by the interface stick-slip behavior and then affect the amplitude-frequency characteristics of the rotor system. Moreover, the torsional vibration of the HP rotor system is more sensitive to the interface stick-slip state, and the continuous frequency spectra and high-order harmonic frequency in the lateral and torsional frequency spectrum of the HP rotor can be used to estimate the interface stick-slip state. Finally, the experimental study is carried out based on a bolted joint dual-rotor test rig to verify some key findings from numerical simulation. The research results can provide valuable insights into the dynamic properties prediction and health monitoring of a bolted joint dual-rotor system.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119254"},"PeriodicalIF":4.3,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144338519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaolan Zhou, Yongxian Wang, Xinghua Cheng, Wei Liu, Houwang Tu
{"title":"Galerkin spectral-element methods for parabolic equations in underwater acoustics with range-dependent environments","authors":"Xiaolan Zhou, Yongxian Wang, Xinghua Cheng, Wei Liu, Houwang Tu","doi":"10.1016/j.jsv.2025.119230","DOIUrl":"10.1016/j.jsv.2025.119230","url":null,"abstract":"<div><div>Accurate modeling of sound propagation is vital for underwater acoustics in ocean exploration and communication. Classical wide-angle parabolic equation models, often discretized using low-order finite difference or finite element schemes, face limitations in accuracy and efficiency. While the Chebyshev-Tau spectral method based SMPE improves accuracy, it requires constant layer thickness during forward stepping, making it unsuitable for range-dependent seafloor problems. To address these limitations, we propose a Galerkin spectral-element methods for solving split-step Padé energy-conserving parabolic equations. Our method relaxes the regularity requirements of solutions, enhances complex boundary condition handling, and generates a symmetric, block-diagonal matrix system, improving computational efficiency. Numerical experiments demonstrate the method’s accuracy and performance, particularly in up-slope propagation simulations in wedge-shaped oceans, where it achieves high-quality results with fewer depth interpolation points and larger range-step sizes. This approach offers a robust and efficient solution for range-dependent underwater acoustic modeling.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119230"},"PeriodicalIF":4.3,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ganesh U. Patil, Hyung-Suk Kwon, Bogdan I. Epureanu, Bogdan-Ioan Popa
{"title":"Synthetically-trained neural networks for shape classification from measured acoustic scattering","authors":"Ganesh U. Patil, Hyung-Suk Kwon, Bogdan I. Epureanu, Bogdan-Ioan Popa","doi":"10.1016/j.jsv.2025.119229","DOIUrl":"10.1016/j.jsv.2025.119229","url":null,"abstract":"<div><div>Drawing inspiration from the biological phenomenon of echolocation, ultrasound perception holds immense potential across various engineering domains, spanning from advanced imaging to precise navigation. Despite advances in sensor development and signal processing, current methodologies struggle to match the remarkable perceptual acuity of echolocating animals when deciphering real-world ultrasound echoes. In this study, we bridge this disparity by harnessing Convolutional Neural Networks (CNNs) to discern ultrasound scattering from objects of different shapes. Our novel approach entails training CNNs using exclusively synthetic data, derived from numerical simulations, to process real echoes. We achieve this through (1) sophisticated data augmentation and processing of synthetic echoes that accommodate physical variations and uncertainties inherent in practical scenarios and (2) specialized CNNs (SCNNs) targeted at each shape to compel models to learn features unique to that shape. Rigorous experimentation demonstrates the ability of these synthetically-trained models to accurately classify fundamental geometric shapes of objects based solely on experimentally measured echoes. Furthermore, the intentional selection of the size and shapes of the objects to produce perceptually similar echoes elucidates the efficacy of our approach in handling intricate perception scenarios. By alleviating laborious and costly data acquisition procedures in favor of synthetic data-driven training for real-world perception, our method opens avenues for advancements in diverse fields reliant on ultrasound-based technologies. These advancements bear implications spanning from diagnostics to the realm of autonomous systems and beyond.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119229"},"PeriodicalIF":4.3,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144253419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Joint measurement of modulus of elasticity and Poisson’s ratio of concrete cubes by actuating special vibration modes: A novel baseline-free technique","authors":"Xiong Sha, Songye Zhu","doi":"10.1016/j.jsv.2025.119288","DOIUrl":"10.1016/j.jsv.2025.119288","url":null,"abstract":"<div><div>Elastic constants (e.g., modulus of elasticity and Poisson’s ratio) of concrete are vital material properties commonly measured by standard static tests (such as the destructive tests of cylinders or prisms), but the corresponding measurement results usually present a large dispersion. In addition, though extensively applied to measure modulus of elasticity, traditional dynamic methods cannot stably measure Poisson’s ratio of concrete, because of their sensitivity to material anisotropy and wall effects of concrete. To overcome these deficiencies, this paper, for the first time, presents a highly accurate method for directly measuring the elastic constants of concrete cubes with high stability using an improved baseline-free electromechanical impedance technique. With the ability of piezoelectric sensors to effectively capture a series of vibration modes of a concrete cube, unique modes can be identified, actuated, and employed for measurement. In this study, a series of numerical analyses were conducted firstly to (a) search anisotropy-insensitive vibration modes of a cube, (b) design corresponding sensor installation strategies for target modes extraction, (c) establish the quantitative evaluation methods, and (d) examine the reliability of the proposed method by considering anisotropy and wall effects. Then, experiments on concrete cubes were performed to show the high accuracy, stability, and reproducibility of the proposed method by comparing it with traditional standard static and dynamic methods.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119288"},"PeriodicalIF":4.3,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144502783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coupled piezoelastic airfoil oscillators: Nonlinear oscillations","authors":"Nishant Nemani , Sergio Preidikman , Balakumar Balachandran","doi":"10.1016/j.jsv.2025.119226","DOIUrl":"10.1016/j.jsv.2025.119226","url":null,"abstract":"<div><div>Limit-cycle oscillations of bodies with airfoil cross-sections is a subject of keen interest for engineering applications. In systems consisting of multiple such closely spaced bodies, the aerodynamic interactions amongst two or more such bodies can influence the system response. The nature of these interactions is examined with respect to variations in external parameters such as freestream speed and system parameters such as inter-oscillator spacing and the number of airfoil oscillators. By using a co-simulation scheme, which consists of a reduced order three degree-of-freedom piezostructural system and an unsteady vortex lattice method fluid solver, the effects of these parameters on the resulting aerodynamic loads on the system, the overall dynamic response, and the critical flutter speed are studied. In a three-airfoil oscillator system, the effect of the position of the inner airfoil oscillator is extensively studied with a focus on characterizing airfoil interactions and airfoil-wake interactions. For different parallel configurations, studies of bifurcations with respect to different control parameters are conducted.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119226"},"PeriodicalIF":4.3,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144261538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Weak stiffness-induced regulation of strongly directional waveguides in anti-tetrachiral spiral metamaterials","authors":"J.C. Guo , J.R. Li , J. Zhao , Z. Zhang","doi":"10.1016/j.jsv.2025.119290","DOIUrl":"10.1016/j.jsv.2025.119290","url":null,"abstract":"<div><div>In-plane weak stiffness and low-frequency strong directional wave regulation at high tensile strains are key considerations for engineering applications. To overcome this problem, a novel anti-tetrachiral spiral metamaterial with low-frequency wave regulation under high tensile strain is designed by introducing Archimedean spiral holes into the perforated plate. The wave attenuation properties and Poisson's ratio characteristics of the proposed anti-tetrachiral spiral metamaterial are investigated through numerical simulations and experimental testing of prototype samples fabricated by additive manufacturing. The results show that weak stiffness is the key factor contributing to the low-frequency bandgap (BG) and zero Poisson's ratio (ZPR) characteristics. The Bragg-type and local resonance-type wave can be interconverted by regulating the stiffness to possess the low-frequency strong wave attenuation capability. The BG frequency of the proposed metamaterial is reduced to 7.88 ‰ of a conventional perforated plate, and its tensile stiffness and maximum mises stress are reduced to 0.23 ‰ and 12.12 ‰ of a conventional perforated plate. Furthermore, the design of four types of waveguide paths with negligible susceptibility to tensile deformation. ZPR structures at weak stiffness have strong directional wave regulation capability in the low-frequency domains, which enables stable wave transport properties independent of tensile deformation. The designed ZPR structures with low in-plane stiffness and low-frequency BG characteristics as well as the strong directional wave regulation are expected to play a key role in the design of future high-performance waveguide devices and tunable BG materials.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119290"},"PeriodicalIF":4.3,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pengfei Ma , Lei Li , Bin Wang , Haifeng Wang , Tong Lin , Yu Liu
{"title":"Reduced-order analysis and data reconstruction of airfoil turbulent acoustic signals using proper orthogonal decomposition and higher-order dynamic mode decomposition","authors":"Pengfei Ma , Lei Li , Bin Wang , Haifeng Wang , Tong Lin , Yu Liu","doi":"10.1016/j.jsv.2025.119286","DOIUrl":"10.1016/j.jsv.2025.119286","url":null,"abstract":"<div><div>This study employs Higher-Order Dynamic Mode Decomposition (HODMD) and Proper Orthogonal Decomposition (POD) to analyze turbulent flow noise characteristics of a Clark-Y airfoil at <em>Rec</em> = 10⁵. By decomposing sound pressure signals, different frequency, direction, and amplitude components of sound waves are extracted for in-depth acoustic analysis. CFD simulations using LES with the WALE model reveal that laminar separation bubbles form at <em>x</em>/<em>c</em> = 0.28 and reattach at <em>x</em>/<em>c</em> = 0.45, generating a turbulent boundary layer and strong pressure fluctuations, identified as the primary source of low-frequency discrete noise. Modal decomposition and reconstruction of experimental sound pressure data across various angles of attack compare HODMD and POD in handling flow-induced noise. Results indicate HODMD effectively extracts dominant frequencies and high-frequency modal structures, while POD, though efficient in energy decomposition, suffers from mode mixing and lacks interpretability in high-frequency noise scenarios. By integrating Sound Pressure Level (SPL) analysis with HODMD, key frequencies associated with boundary layer transition noise are identified, revealing their time-evolution characteristics. The study highlights HODMD’s superiority in capturing dynamic evolution and stable modes of airfoil noise, providing valuable insights for aeroacoustic noise prediction and control strategies.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"618 ","pages":"Article 119286"},"PeriodicalIF":4.3,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144261320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Compound nonlinear energy sink with multiple motion types for absorbing energy from wide excitation ranges","authors":"Jianen Chen , Jiaqi Zhao , Wei Zhang , Min Sun","doi":"10.1016/j.jsv.2025.119273","DOIUrl":"10.1016/j.jsv.2025.119273","url":null,"abstract":"<div><div>Nonlinear energy sink (NES) has garnered significant attention since its inception due to its notable broadband vibration reduction capability. However, the introduction of strong nonlinear characteristics by NESs complicates system responses, leading to a loss of effectiveness when the excitation force exceeds a specific threshold. Consequently, NESs have limited applicability in engineering because they are effective only within a constrained range of excitation amplitude. In this study, a compound NES (CNES) with multiple motion types is designed to extend the effective force range while maintaining broadband vibration reduction capability. The CNES is distinguished by its piecewise stiffness, collision mechanisms, and unique design of two-degree-of-freedom oscillators. The wide effective range of the CNES is demonstrated through slow linear sweep and fixed-frequency tests. The results indicate that the CNES effectively reduces vibrations in the primary oscillator (PO) with various resonant frequencies. Notably, the CNES achieves significant vibration reduction over a particularly wide range of excitation amplitude when controlling the PO with relatively high resonance frequencies (approximately 10.5 Hz and 19 Hz). However, a nonnegligible limitation of the CNES is its restricted effective range of excitation amplitude when the PO resonates at lower frequency (approximately 7 Hz). Moreover, five motion types of the CNES are identified and analyzed, with one motion type autonomously emerging in response to changes in excitation parameters, ensuring excellent vibration reduction performance across a wide excitation range. Finally, the performance of the CNES and a degraded single-degree-of-freedom CNES are compared to further demonstrate the extension effect of the multiple motion types on the effective range. The CNES can be used in scenarios where the parameters of protected systems and excitations vary widely, providing a thought to improve the NESs.</div></div>","PeriodicalId":17233,"journal":{"name":"Journal of Sound and Vibration","volume":"617 ","pages":"Article 119273"},"PeriodicalIF":4.3,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144279154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}