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Influence of hydrofoil characteristic thickness on the cavitation erosion risk distribution of clearance vortex cavitation and its mechanisms

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Journal of Hydrodynamics 2025年第1期37卷 50-62页

作者： Huang, Jia-Le Cheng, Huai-Yu Cao, Yan-Tao Ji, Bin State Key Laboratory of Water Resources Engineering and Management Wuhan University Wuhan430072 China National Key Laboratory on Ship Vibration & Noise China Ship Scientific Research Center Wuxi214082 China Taihu Laboratory of Deepsea Technological Science Wuxi214082 China

To clarify the influence of the hydrofoil characteristic thickness on the distribution characteristics and mechanisms of clearance cavitation erosion risk, a large eddy simulation (LES) is conducted to study the clearance cavitating flow around NACA0012 and NACA0024 hydrofoils under identical conditions. The study predicts cavitation erosion risk using three methods: The erosive power method (EPM), the improved gray level method (IGLM) and the energy conservation method (ECM). The numerical results are in good agreement with the experiment data and the ECM is applied due to its simplicity in parameter adjustment and low sensitivity. The results indicate that the characteristic thickness significantly influences the flow field, leading to variations in the position and intensity of cavitation collapse, ultimately resulting in notable differences in cavitation erosion risk distribution. The high cavitation erosion risk region on the clearance surface of NACA0012 is concentrated around the midsection, while it is concentrated in the upstream region for the NACA0024, with a lower frequency of extreme events. Tip separation vortex (TSV) cavitation is the main cause of the differences in cavitation erosion risk distribution. On the clearance surface of the NACA0012, TSV cavitation primarily collapses in the central region, whereas for the NACA0024 hydrofoil, TSV cavitation occurs only in the upstream region of the clearance surface and exhibits more stability. The differences in vorticity distribution near the clearance surface partially influence the distribution of TSV cavitation, thereby affecting the characteristics of cavitation erosion risk distribution. The larger characteristic thickness of the NACA0024 reduces the effects of the stretching term and the baroclinic torque term, weakening the effect of vorticity on TSV cavitation, resulting in more stable patterns of the TSV cavitation. © China ship Scientific Research Center 2025.

关键词： Energy Intensity

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Observation of tunable exceptional points in a non-Hermitian acoustic system

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science China(Physics,Mechanics & Astronomy) 2025年第5期68卷 143-150页

作者： Chen Liu Zhongming Gu Haixiao Zhang Xiaowei Zhang Chuanhao Ge Tuo Liu Jie Zhu Institute of Acoustics School of Physics Science and EngineeringTongji UniversityShanghai 200092China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of Physics MOE Key Laboratory of Modern AcousticsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China School of Electrical and Information Engineering Changzhou Institute of TechnologyChangzhou 213032China Key Laboratory of Speech Acoustics and Content Understanding Institute of AcousticsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China 7. Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China

Exceptional points(EPs)have extensive and important applications in many wave-based technologies,such as ultra-sensitive sensing,unidirectional scattering and low-threshold ***,most of the previous EP-related wave phenomena are demonstrated in systems with fixed configuration,thereby extremely constraining their adaptability and reconfigurability in ***,we introduce a flexible approach to tuning EPs in an acoustic system with sandwich structures.A rotatable component,associated with an alterable gradient index,is clamped by a pair of lossy acoustic *** derivations and numerical simulations validate the capabilities of the model in continuously regulating EPs in the parameter space,with ingenious experimental setups confirming these *** results showcase the system's effectiveness in achieving unidirectional reflectionless wave propagation across various *** research reveals a flexible approach to linking the adjustment of EPs to a simple structural parameter,offering a robust framework for exploring and implementing non-Hermitian wave phenomena in practical scenarios.

关键词： asymmetric reflection tunable exceptional points non-Hermitian acoustic system

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BiCG: Binaural Cue Generation from Unified HRTF Datasets

BiCG: Binaural Cue Generation from Unified HRTF Datasets

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Xikun Lu Yilei Wang Jinqiu Sang Chengshi Zheng Lab of Artificial Intelligence for Education East China Normal University China School of Computer Science and Technology East China Normal University China Key Laboratory of Noise and Vibration Research Institute of Acoustics Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Head-related transfer functions (HRTFs) are important for spatial audio reproduction in immersive systems. Most existing data-driven methods focus on personalized HRTF estimation of monaural spectral factors. These methods ignore the importance of binaural cues, which are essential for binaural reproduction and perception. Moreover, the significant differences among various HRTF datasets in aspects such as measurement setup limit the potential of data-driven methods. This paper proposes a binaural cue generation method (BiCG), which utilizes an implicit neural network (INN) to estimate interaural level differences (ILDs) and interaural time differences (ITDs). Experimental results show that our method outperforms existing neural field methods in terms of binaural cue generation quality across datasets. We also evaluate various data preprocessing methods, and experimental results show that extreme smoothing improves binaural cue generation performance across datasets. The work provides new insights into enhancing HRTF modeling.

关键词： Smoothing methods Spatial audio Neural networks Data preprocessing Transfer functions Estimation Signal processing Acoustics Copper Speech processing

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Experiment on surface wake of internal waves generated by underwater vehicle in stratified fluids

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Journal of Hydrodynamics 2022年第2期34卷 277-285页

作者： Zhi-chong Yao Jun Zhang De-bao Gao Chuan-qi Liu Fang-wen Hong China Ship Scientific Research Center Wuxi214082China TaiHu Laboratory on Deep Sea Technology and Science Wuxi214082China National Key Laboratory on Ship Vibration and Noise Wuxi214082China

The surface flow field of internal waves generated by the underwater vehicle is very *** order to study the characteristics of the surface wake of internal waves,a surface particle image velocimetry(PIV)technique which can be used to measure the flow field in the order of mm/s is *** is made with respect to the key technique measuring the micro-velocity flow field of internal waves on the water surface in stratified *** wake generated by SUBOFF model is measured in stratified fluid tank,and the surface flow field of internal waves is successfully measured for the first *** experimental results are compared with predicted results by the classical Tuck’s internal wave *** results show the characteristics of the surface wake signature of internal waves and the variation of the angle between internal wave beams and the surface flow velocity of internal wave with the towing speed of the model are in good *** provides support for further research on wake signature remote sensing of internal waves in laboratory.

关键词： Stratified fluids surface wake signature internal waves experimental research

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An experimental study on the impact behavior of cavitation inside tip clearance of a hydrofoil

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Journal of Hydrodynamics 2023年第6期35卷 1208-1214页

作者： Yan-tao Cao Liang-hao Xu Xiao-xing Peng National Key Laboratory on Ship Vibration and Noise China Ship Scientific Research CenterWuxi214082China Taihu Laboratory of Deepsea Technological Science Wuxi214082China

Tip clearance cavitation is one of the most common cavitation phenomena exist on duct propellers,pumps and some hydraulic turbines,which may lead to erosion of the *** to the influence of the nearby wall,cavitation inside the tip clearance is more complicated than other cases without *** far,the understanding about the impact mechanism of tip clearance cavitation is still *** this paper,to obtain the impact behavior of tip clearance cavitation,a high-speed camera was used to capture the cavitation behavior inside the tip clearance of a hydrofoil,and surface paint coating peeling method was applied to show the impact *** indicated that cavitation around the tip of the hydrofoil was composed of a tip separation cavity and a tip leakage vortex cavity,and the one with contribution to impact was the tip separation *** the comprehensive analysis of the paint peeling region and dynamic behavior of tip separation cavity,the impact was found to be related to the local collapse and rebound of the cloud cavitation shed from the attached *** addition,the influence of tip clearance size on the behavior of tip clearance cavitation was also *** the tip clearance size increased,the tip separation cavity tended to transfer from sheet cavitation to vortex *** findings can provide a sound basis for evaluating the erosion risk arising from the tip clearance cavitation.

关键词： Tip clearance cavitation impact region impact behavior tip clearance size

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A new statistical model of wave heights based on the concept of wave breaking critical zone

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Acta Oceanologica Sinica 2015年第5期34卷 81-85页

作者： YANG Jiaxuan LI Xunqiang ZHU Shouxian ZHANG Wenjing WANG Lei Institute of Noise and Vibration Naval University of Engineering Institute of Meteorology and Marine PLA University of Science and Technology National Key Laboratory on Ship Vibration and Noise College of Harbour Coastal and Offshore EngineeringHohai University

When waves propagate from deep water to shallow water, wave heights and steepness increase and then waves roll back and break. This phenomenon is called surf. Currently, the present statistical calculation model of surf was derived mainly from the wave energy conservation equation and the linear wave dispersion relation, but it cannot reflect accurately the process which is a rapid increasing in wave height near the broken point. So, the concept of a surf breaking critical zone is presented. And the nearshore is divided as deep water zone, shallow water zone, surf breaking critical zone and after breaking zone. Besides, the calculation formula for the height of the surf breaking critical zone has founded based on flume experiments, thereby a new statistical calculation model on the surf has been established. Using the new model, the calculation error of wave height maximum is reduced from 17.62% to 6.43%.

关键词： wave height statistical model surf breaking critical zone flume experiments

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Numerical assessment of the erosion risk for cavitating twisted hydrofoil by three methods

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Journal of Hydrodynamics 2021年第4期33卷 698-711页

作者： Ting-ting Lei Huai-yu Cheng Bin Ji Xiao-xing Peng State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China National Key Laboratory on Ship Vibration and Noise China Ship Scientific Research CenterWuxi214082China

In this paper, the large eddy simulation (LES) method in conjunction with the Zwart cavitation model is adopted for the assessment of the erosion risk on a hydrofoil surface. The numerical results are in good agreement with the experiments. On this basis, three methods, namely the intensity function method (IFM), the time-averaged aggressiveness indicators (TAIs) and the gray level method (GLM), are applied for the assessment of the erosion risk. It is shown that the erosion intensity index of the IFM is extremely sensitive to the artificially selected thresholds, which greatly limits the application of the method. The erosion risk predicted by four indicators in the TAIs does not agree well with the experimental results. Further analysis demonstrates that the GLM using the instantaneous pressure field is relatively satisfactory, which can provide a reasonable assessment of the erosion and is not very sensitive to the artificially selected thresholds. To further improve the accuracy of the GLM for the erosion risk prediction, the time-average pressure field is adopted in the GLM for the erosion evaluation. It is suggested that the erosion assessment by using the time-averaged pressure field is in better agreement with the experimental results when compared with that by using the instantaneous pressure field.

关键词： Cavitating flow erosion numerical simulation threshold selection

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Experimental investigation of vortex generator influences on propeller cavitation and hull pressure fluctuations

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Journal of Hydrodynamics 2020年第1期32卷 82-92页

作者： Hong-bo Huang Yun Long Bin Ji National Key Laboratory on Ship Vibration and Noise China Ship Scientific Research CenterWiuxi 214082China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China

In this paper,the transient turbulent cavitating flow around a marine propeller behind a ship was investigated experimentally with emphasis on how vortex generator(VG)influences propeller cavitation and hull pressure *** experiments were carried out in China Large Cavitation Channel with the closed test section covering 10.5 m in length and cross-section of 2.2 m^2×2.0m^*** experiment recorded instantaneous cavitation photos of the propeller and pressure fluctuations on the hull *** results demonstrate that without vortex generator,the sheet cavitation inception begins at-50°(310°),and then from-50°(310°)to 30°,the extent and area of sheet cavitation *** vortex generator installed on the hull,the sheet cavitation inception occurs in advance at-60°(300°),and the sheet cavitation expands to larger rotation range due to the vortex *** is shown that the vortex generator with proper geometry and installed location may contribute the highly nonuniform wake to be more uniform,and can make the change of propeller cavitation to be milder,which decrease the pressure fluctuations in this *** analysis indicates that the vortex generator may promote the energy distribution to be more uniform in physical and spectral space in some degree.

关键词： Cavitating flow pressure fluctuations propeller and ship hull vortex generator

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A fast prediction method of acoustic radiation from elastic cylindrical shell in shallow water 24

A fast prediction method of acoustic radiation from elastic ...

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24th International Congress on Sound and vibration, ICSV 2017

作者： Chen, Hongyang Li, Qi Shang, Dejiang Wang, Hao China Ship Development and Design Center Science and Technology of Ship Vibration and Noise on Key Laboratory Wuhan China Harbin Engineering University Underwater Acoustic Science and Technology Laboratory Harbin China Science and Technology of Ship Vibration and Noise on Key Laboratory Wuhan China

In order to predict acoustic radiation from an elastic structure in shallow water, a method based on wave superposition is proposed, in which the free-space Green function is used to match the strength of equivalent sources. Necessary treatment is conducted in order to neglect the effect of sound reflection from boundaries, which makes the method more efficient. Moreover, the method is combined with the sound propagation algorithms to predict the sound radiated from a elastic cylindrical shell in Pekeris waveguide. The cylindrical shell with hemi-cap is taken as an example to illustrate the validity of the proposed method. Numerical simulations show that the proposed method has robust and efficient in computation.

关键词： Forecasting

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Numerical-analytical hybrid calculation method for acoustic radiation of underwater vehicles with internal vibration isolation system

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Journal of Sound and vibration 2025年 615卷

作者： Ming-Song Zou Huai-Cheng Tang Yi-Ni Yang Si-Long Peng Zhi-Yong Yin China Ship Scientific Research Center Wuxi 214082 China Taihu Laboratory of Deepsea Technological Science Wuxi 214082 China State Key Laboratory of Deep-sea Manned Vehicles Wuxi 214082 China National Key Laboratory on Ship Vibration and Noise Wuxi 214082 China

The application of floating raft isolation technology can effectively reduce mechanical noise in ships and underwater vehicles. Mastering accurate design calculation methods is key to further improving the vibration reduction and noise reduction performance of floating raft systems. More efficient modeling and solving techniques, broader frequency range applicability, and more accurate simulation of isolation components are the current focal points in the research and practical application of design calculation methods for floating raft systems. This paper proposes a hybrid multi-layer substructure integration method, combining analytical and numerical techniques, to improve the computational efficiency of vibration and acoustic radiation analysis in underwater vehicles with vibration isolation systems. The underwater vehicle is divided into a main hull (stiffened cylindrical shell) and internal multi-layer substructures (base, isolators, floating raft, etc.). The main hull is solved analytically, while the base and floating raft are modeled using modal synthesis super-element method to obtain dynamic stiffness matrices. The isolator is modeled using the four-terminal parameter method. These substructures are then integrated to compute the overall structure's vibration and acoustic radiation. For scenarios where the internal vibration isolation system is modified, only the local substructure needs to be recalculated and coupled with the rest of the structure, improving efficiency while maintaining accuracy. This method addresses the frequency limitation bottlenecks of pure numerical methods, extending the frequency range to several kilohertz and enabling significant breakthroughs in broadband applicability. The dynamic stiffness matrices of floating raft isolators, which can be obtained from experimental tests, enhance the method's practical engineering value. The validity of the proposed method is verified through numerical examples and experimental comparisons, an

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