Article
Engineering, Marine
Qi Wang, Lin -Han Feng, Nian-Nian Liu, Mao Li, Peng-Duo Zhao, Lei Zhang, Shi-Ping Wang
Summary: In this paper, a series of experiments were conducted to investigate the complex behaviors of a collapsing bubble near a vertical rigid wall in an underwater explosion tank. The evolution of the bubble was captured by a high-speed camera, and the pressure on the wall surface caused by the shock wave and bubble collapse was measured by sensors. The experimental results were compared with theoretical results, showing good agreement. The effects of bubble-wall distance on bubble behaviors and explosion load characteristics on the rigid surface were analyzed.
Article
Engineering, Marine
Zhichao Lai, Shuo Deng, Jian Qin, Hui Chi, Xiangyao Meng, Xiaoqiang Yang, Ruiyuan Huang
Summary: The wall pressure generated by near-field underwater explosion bubble is a significant nonlinear problem and a focus of research in battleship anti-explosion design. Underwater explosion tests were conducted to quantify the load characteristics of bubble pulsation and water jet pressure. A finite element model was established and benchmarked to explore these load characteristics. It was found that plate dimension and stand-off distance have an impact on the pressure and impulse of the bubble pulsation and water jet.
Article
Engineering, Multidisciplinary
Hong-Wei Hu, Pu Song, Shuang-feng Guo, Hai-yun Feng, Dao-kui Li
Summary: The study focuses on the effect of underwater explosion parameters on the multi-point array explosion. Shock wave and bubble parameters of aggregate charge, two charges, and four charges were measured through underwater explosion tests, and their influence on the explosion power field in terms of charge quantity and array distance was analyzed.
DEFENCE TECHNOLOGY
(2022)
Article
Engineering, Marine
Jun Yu, Guo-zhen Liu, Jun Wang, Hai-kun Wang
Summary: This study presented a novel and efficient method to simulate bubble jet induced by underwater explosion near the wall, which was validated and applied successfully.
Article
Engineering, Multidisciplinary
Ching-Yu Hsu, Cho-Chung Liang, Vo-Phuong Duy
Summary: This study proposes a dynamic approach for simulating underwater explosions using the Finite Element Method and the Eulerian-Lagrangian method. Numerical analysis shows promising results and indicates the potential of this approach in predicting outcomes of underwater explosions with high pressure bubbles and studying their behavior near complex structures. This research contributes to further studies on the topic.
JOURNAL OF ENGINEERING RESEARCH
(2022)
Article
Engineering, Marine
P. R. Nowak, A. Szlachta, T. Gajewski, P. Peksa, P. W. Sielicki
Summary: Research studies on blast loads under the water surface are less common compared to those in the air, and addressing this gap in knowledge can enhance the safety of marine structures, military divers, and personnel working underwater. This study conducted field experiments in a shallow-water tank to investigate the pressure parameters, gas bubble formation, and behavior of the blast wave. The influence of cavitation formation on pressure propagation in a limited water medium was also analyzed.
Article
Chemistry, Multidisciplinary
Yuxiang Gong, Wenpeng Zhang, Zhipeng Du, Yinghao Zhu
Summary: The pulsation of bubbles from underwater explosions can cause significant damage to the ship's hull structure, including sinking. In this study, the Coupled Eulerian-Lagrangian (CEL) method was used to simulate 11 simplified hull girder (SHG) structures subjected to near-field underwater explosion bubbles, ensuring calculation accuracy. The sagging bend mechanism of SHGs was analyzed from the perspective of plastic hinge lines, and the length formula of the potential bend zone was determined. The impact of transverse bulkheads on bending mode and total longitudinal strength was also investigated.
APPLIED SCIENCES-BASEL
(2023)
Article
Engineering, Marine
Yuxiang Gong, Wenpeng Zhang, Zhipeng Du, Jianwei He
Summary: In this study, the damage mechanism of a simplified hull girder (SHG) under near-field underwater explosion is analyzed using the Coupled Eulerian-Lagrangian (CEL) method. The finite element model is verified for accuracy. The progressive sagging damage and plastic hinge lines of SHGs under near-field explosions are investigated, and theoretical derivations based on the plastic hinge line model are carried out. The results show that stable creases, mainly in a W shape, appear in the midship when the SHGs experience sagging damage from the near-field underwater explosion bubble load.
Article
Nanoscience & Nanotechnology
Chao Zhang, Zhaoqin Yin, Chengxu Tu, Zeming Huang, Taohou Chen, Fubing Bao, Junliang Lu, Xianfu Ge
Summary: This study investigates the bubble cavitation dynamics between a rigid wall and an elastic wall, obtaining different bubble collapse patterns by varying the distance between the walls and the initial position of the bubble. Changes in migration distance, gravity, and maximum radius during cavitation are discussed, and numerical simulation successfully confirms the appearance of satellite bubbles during the bubble collapse process between the walls. The pressure of the satellite bubble and the elastic wall are obtained from the simulation, explaining the formation of the satellite bubble.
Article
Engineering, Civil
Xinying Zheng, Haitao Li, Yi Zhu, Yansong Lv, Chi Zhang, Zhiyuan Mei
Summary: This paper investigates the influence of superstructure on the damage characteristics of ships subjected to a near field underwater explosion. Two hull girder models with different superstructures were designed and experimentally and numerically analyzed. The study discusses the impact of structural modifications and layout changes of the superstructure on the hull girder's damage and explores the overall and local coupling damage characteristics of the hull. The numerical simulations accurately predict the hull girder's damage mode and deformation and show that the presence of the superstructure increases the hull girder's resistance to bending deformation and reduces the damage to the hull bottom grillage.
THIN-WALLED STRUCTURES
(2023)
Article
Engineering, Marine
Yuxiang Gong, Wenpeng Zhang, Zhipeng Du
Summary: Investigating the responses of simplified hull girder (SHG) structures subjected to underwater explosions can provide valuable insights for real ships. Experimenting with an SHG that closely approximates the relative thickness of plates found in real ships, the researchers conducted underwater explosion tests to examine damage mechanisms. Through simulations and analysis, they discussed the damage mechanisms and collapse modes of the SHGs, providing prediction formulas for estimating core damage zone sizes. The results showed that the thinner-walled SHG exhibited more complex damage phenomena resembling those observed in real ships.
Article
Thermodynamics
Thanh-Hoang Phan, Van -Tu Nguyen, Trong-Nguyen Duy, Dong-Hyun Kim, Warn-Gyu Park
Summary: This study numerically investigates the thermodynamic and hydrodynamic mechanisms of underwater explosion (UNDEX), accurately simulating the evolution of bubbles and temperature fields and verifying the model's accuracy. The results show good agreement with analytical solutions and experimental data, revealing the temperature changes inside the collapsing bubble and the characteristics of the thermal boundary layer. The effects of initial equilibrium gas temperature and water temperature on UNDEX mechanisms are investigated, proposing a nonlinear relationship among key parameters.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Marine
Liu-Yi Xu, Shi-Ping Wang, Yun-Long Liu, A-Man Zhang
Summary: This paper investigates the effects of underwater explosions in shallow water, with a focus on the impact of a deformable seabed on bubble motion and shockwave propagation. The study uses numerical models and simulations to show that the density ratio and initial charge depth have a positive relation to bubble period and pressure peak. Additionally, the presence of an annular jet during the contraction phase could lead to bubble splitting under certain conditions.
Article
Engineering, Multidisciplinary
Hai-tao Li, Xin-ying Zheng, Chi Zhang, Zhi-yuan Mei, Xue-fei Bai, Kai Liu
Summary: A trapezoidal hull girder was designed, manufactured, and tested to investigate the damage characteristics and failure modes of a warship in an underwater non-contact near-field explosion. Results showed that the girder mainly exhibited sagging damage, with the largest deformation observed when the explosion occurred directly below the midspan of the girder. The ratio of stand-off to maximum bubble radius was found to affect the type and magnitude of girder deformation, with sagging deformation increasing at higher ratios and decreasing at lower ratios. The low-pressure region of the flow field formed by bubble pulsation and the resonant coupling between the girder and the bubble were identified as the main causes of damage to the overall girder structure.
DEFENCE TECHNOLOGY
(2023)
Article
Engineering, Marine
Zhifan Zhang, Hailong Li, Longkan Wang, Guiyong Zhang, Zhi Zong, Shenhe Zhang
Summary: The damage characteristics of underwater explosion-generated shock wave, shaped charge projectile (SCP) and bubble into double-hull structure are analyzed. The protection of fiber metal laminates (FML) is discussed. The results show that the FML can prevent the tearing and penetration of shaped charge projectile, while the bubble load is effectively stopped by coated polyethylene (PE), indicating a great protection performance.
Article
Engineering, Marine
Alba Ricondo, Laura Cagigal, Beatriz Perez-Diaz, Fernando J. Mendez
Summary: This research presents a site-specific metamodel based on the SWASH numerical model simulations, which can predict coastal hydrodynamic variables in a fast and efficient manner. The metamodel uses downscaled and dimensionality reduced synthetic database to accurately reproduce wave setup, wave heights associated with different frequency bands, and wave runup. This method has great potential in coastal risk assessments, early warning systems, and climate change projections.
Article
Engineering, Marine
Xiao Yu, Wangjun Ren, Bukui Zhou, Li Chen, Xiangyun Xu, Genmao Ren
Summary: This study investigated and compared the compression responses and energy absorption capacities of coral sand and silica sand at a strain rate of approximately 1000 s-1. The results showed that coral sand had significantly higher energy absorption capacity than silica sand due to its higher compressibility. The study findings suggest that using poorly graded coral sand can improve its energy absorption capacity.
Article
Engineering, Marine
Jingxi Zhang, Junmin Mou, Linying Chen, Pengfei Chen, Mengxia Li
Summary: This paper proposes a cooperative control scheme for ship formation tracking based on Model Predictive Control. A predictive observer is designed to estimate the current motion states of the leader ship using delayed motion information. Comparative simulations demonstrate the effectiveness and robustness of the proposed controller.
Article
Engineering, Marine
Yu Yao, Danni Zhong, Qijia Shi, Ji Wu, Jiangxia Li
Summary: This study proposes a 2DH numerical model based on Boussinesq equations to investigate the impact of dredging reef-flat sand on wave characteristics and wave-driven current. The model is verified through wave flume experiments and wave basin experiments, and the influences of incident wave conditions and pit morphological features on wave characteristics are examined.
Article
Engineering, Marine
Jayanta Shounda, Krishnendu Barman, Koustuv Debnath
Summary: This study investigates the double-average turbulence characteristics of combined wave-current flow over a rough bed with different spacing arrangements. The results show that a spacing ratio of p/r=4 offers the highest resistance to the flow, and the double-average Reynolds stress decreases throughout the flow depth. The advection of momentum-flux of normal stress shows an increase at the outer layer and a decrease near the bed region after wave imposition. Maximum turbulence kinetic energy production and diffusion occur at different layers. The turbulence structure is strongly anisotropic at the bottom region and near the outer layer, with a decrease in anisotropy observed with an increase in roughness spacing.
Article
Engineering, Marine
Meng Zhang, Lianghui Sun, Yaoguo Xie
Summary: The research proposes a method for online identification of wave bending and torsional moment in hull structures. For structures without large openings, the method optimizes sensor positions and establishes a mathematical model to improve accuracy. For structures with large openings, a joint dual-section monitoring method is proposed to simultaneously identify bending and torsional moments in multiple key cross sections.
Article
Engineering, Marine
Longming Chen, Shutao Li, Yeqing Chen, Dong Guo, Wanli Wei, Qiushi Yan
Summary: This study investigated the dynamic response characteristics and damage modes of pile wharves subjected to underwater explosions. The results showed that the main damaged components of the pile wharf were the piles, and inclined piles had a higher probability of moderate or more significant damage compared to vertical piles. The study also suggested that replacing inclined piles with alternative optimized structures benefits the blast resistance of pile wharves.
Article
Engineering, Marine
I. -C Kim, G. Ducrozet, V. Leroy, F. Bonnefoy, Y. Perignon, S. Bourguignon
Summary: Previous research focused on the accuracy and efficiency of short-term wave fields in specific prediction zones, while we developed algorithms for continuous wave prediction based on the practical prediction zone and discussed important time factors and strategies to reduce computational costs.
Article
Engineering, Marine
Hang Xie, Xianglin Dai, Fang Liu, Xinyu Liu
Summary: This study investigates the load characteristics of a three-dimensional stern model with pitch angle through a drop test, and reveals complex characteristics of pressure distribution near the stern shaft. The study also shows that the vibration characteristics of the load are influenced by the drop height and pitch angle, with the drop height having a greater effect on the high-frequency components.
Article
Engineering, Marine
Hangyuan Zhang, Wanli Yang, Dewen Liu, Xiaokun Geng, Wangyu Dai, Yuzhi Zhang
Summary: The deep-water bridge is more vulnerable to earthquake damage than the bridge standing in air. The larger blocking ratio has a significant impact on the added mass coefficient, which requires further comprehensive study. The generation mechanism of block effect is analyzed using numerical simulation software ANSYS Fluent. The results show that the recirculation zone with focus reduces the pressure on the back surface of the cylinder, resulting in the peak value of in-line force not occurring synchronously with the peak value of acceleration. The change in position and intensity of the recirculation zone with focus, as well as the change in water flow around the cylinder surface, are identified as the generation mechanism of the block effect, which has a 10% influence on the hydrodynamic force. The changing rule of the added mass coefficient with blocking ratio is discussed in detail, and a modification approach to the current added mass coefficient calculation method is suggested. Physical experiments are conducted to validate the modification approach, and the results show that it is accurate and can be used in further study and real practice.
Article
Engineering, Marine
Golnesa Karimi-Zindashti, Ozgur Kurc
Summary: This study examines the performance of an in-house code utilizing a deterministic vortex method on the rotation of circular and square cylinders. The results show that rotational motion reduces drag forces, suppresses fluctuating forces, and increases lift forces. The code accurately predicts vortex shedding suppression and identifies the emergence of near-field wakes in the flow over rotating square cylinders.
Article
Engineering, Marine
George Dafermos, George Zaraphonitis
Summary: The survivability of damaged ships is of great importance and the regulatory framework is constantly updated. The introduction of the probabilistic damage stability framework has rationalized the assessment procedure. Flooding simulation tools can be used to investigate the dynamic response of damaged ships.
Article
Engineering, Marine
Xuyue Chen, Xu Du, Chengkai Weng, Jin Yang, Deli Gao, Dongyu Su, Gan Wang
Summary: This paper proposes a real-time drilling parameters optimization method for offshore large-scale cluster extended reach drilling based on intelligent optimization algorithm and machine learning. By establishing a ROP model with long short-term memory neurons, and combining genetic algorithm, differential evolution algorithm, and particle swarm algorithm, the method achieves real-time optimization of drilling parameters and significantly improves the ROP.
Article
Engineering, Marine
Sung-Jae Kim, Chungkuk Jin, MooHyun Kim
Summary: This study investigates the dynamic behavior of a moored submerged floating tunnel (SFT) under tsunami-like waves through numerical simulations and sensitivity tests. The results show that design parameters significantly affect the dynamics of the SFT system and mooring tensions, with shorter-duration and higher-elevation tsunamis having a greater impact.
Article
Engineering, Marine
G. Clarindo, C. Guedes Soares
Summary: Environmental contours are constructed using the Inverse-First Order Reliability Method based on return periods. The paper proposes the use of the Burr distribution to model the marginal distribution of long-term significant wave heights. The newly implemented scheme results in different environmental contours compared to the reference approach.