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An efficient and accurate numerical method for simulating close-range blast loads of cylindrical charges based on neural network

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Defence Technology(防务技术) 2025年第2期44卷 257-271页

作者： Ting Liu Changhai Chen Han Li Yaowen Yu Yuansheng Cheng School of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Naval Architecture and Ocean Engineering Hydrodynamics Wuhan 430074China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China

To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was *** NNS method consisted of three main ***,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical ***,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural ***,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and *** reliability of the proposed NNS method was verified by related experimental *** accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP ***,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL *** proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical *** proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.

关键词： Close-range air blast load Cylindrical charge Numerical method Neural network CEL method CONWEP model

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Analysis of Rudder Force Characteristics under Different Drift Angles and Propeller Faults 34th

Analysis of Rudder Force Characteristics under Different Dri...

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34th International ocean and Polar engineering Conference, ISOPE 2024

作者： Li, Pengfei Zou, Yanlin Cai, Zichao Wang, Xunming Feng, Dakui School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653784

In the present study, RANS method and K-omega turbulence model are used to simulate the force characteristics of rudder under different drift angles and propeller faults. K-omega turbulence model includes two extra transport equations to represent the turbulent properties of the flow. A validation calculation is performed on the open water performance of the propeller to compare with the EFD data. Considering the sailing conditions, three different drift angles are taken into account. The thrust on the propeller and the forces on the rudder are calculated and studied under different rudder angles and drift angles. A comparative analysis was conducted on the velocity distribution and rudder forces under two different types of propeller faults. © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Rudders

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Study on nonlinear numerical wave tank based on boundary generation method 34th

Study on nonlinear numerical wave tank based on boundary gen...

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34th International ocean and Polar engineering Conference, ISOPE 2024

作者： Liu, Wuyang Yao, Chaobang Yu, Jiawei Feng, Dakui Zhang, Zhiguo School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653784

The establishment of a numerical wave tank is a crucial step in carrying out simulations of ship sea keeping performance using computational fluid dynamics (CFD) method. Based on the in-house viscous solver HUST-SHIP, a three-dimensional numerical wave tank is constructed based on the fifth-order Stokes wave theory by using the boundary wave generation approach. The wave-generation performance of the tank is verified, and the nonlinear regular waves that can propagate stably and continuously for a long time are obtained. The effects of grid, time step and wave steepness on the simulation results are studied, and the optimal simulation strategy for different wave steepness is determined. The research results can provide a more realistic wave environment for simulating and predicting the motion response of ships under different sea conditions. © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Numerical methods

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Numerical Study of ocean Current effect on the Motion of Underwater Glider 34th

Numerical Study of Ocean Current effect on the Motion of Und...

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34th International ocean and Polar engineering Conference, ISOPE 2024

作者： Bai, Tiechao Ma, Yongyan Yu, Jiawei Zhang, Zhiguo School of Naval Architecture and Ocean Engineering Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781880653784

In this paper, numerical simulation of the vertical-plane gliding of underwater gliders were conducted under the current based on dynamic structure overset grid technique and the SST k-ω turbulence model. The simulation focused on the speed, displacement and attitude during the underwater glider diving process. Different of net buoyancy and the relative position of the center of gravity of underwater gliders was studied. The changes of glider's attitude fromthe adjustment of the heavy buoyancy were presented. Then, numerical analysis of the gliding performance under different ocean current velocities is conducted. The speed, displacement and attitude of underwater gliders under different ocean current speeds are compared and analyzed. © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： ocean currents

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The capillary pressure curves from upscaling interfacial and unsaturated flows in porous layers with vertical heterogeneity

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Theoretical & Applied Mechanics Letters 2023年第4期13卷 287-290页

作者： Zhong Zheng State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Hydrodynamics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(***,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential *** capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection *** with the relative permeability curves k_(rn)(s)that are already *** can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.

关键词： Flow upscaling Interfacial and unsaturated flow Wetting and capillary effects Porous layer Heterogeneity

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Numerical Study of The Propeller Performance with Twin Rudder System 33rd

Numerical Study of The Propeller Performance with Twin Rudde...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Huang, Yaofeng Li, Jing Zhang, Donglei Wang, Xianzhou School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of ship and ocean hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653807

As a novel energy-saving device, the Gate Rudder System with asymmetric wing section can provide extra thrust to the ship and improve the maneuvering performance of the ship. In the present study, a similar twin rudder system with symmetric wing section is designed based on the Gate Rudder System. Model-scale open-water simulations of KP505 propeller at have been conducted for validation. The propeller openwater performance with the twin rudder considering different design angles and different lateral distances have been obtained. The comparison of the effects of conventional rudder and the twin rudder on propeller performance have been conducted and analyzed. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Propellers

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Numerical Simulation of Intact and Damaged Ship Motions in Head Waves 33rd

Numerical Simulation of Intact and Damaged Ship Motions in H...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Li, Jing Huang, Yaofeng Dong, Kai Wang, Xianzhou School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of ship and ocean hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653807

In order to investigate the seakeeping performance of naval ships, this study presents numerical simulations on the prediction of motions for the DTMB 5415 model at zero speed in intact and damaged conditions under head waves. Wave heights of simulations have been verified and validated. The harmonic response amplitude operators (RAOs) of heave and pitch responses for intact and damaged ships are acquired and compared with the experimental results. The comparisons of the intact and damaged ship motions under different wave circular periods are analyzed. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Numerical models

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Numerical Study on Vortex-Induced Motion of Underwater Mooring Platform under the Influence of Multiple Parameters 33rd

Numerical Study on Vortex-Induced Motion of Underwater Moori...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Deng, Weihua Zou, Yanlin Wang, Xunming Xiang, Han Feng, Dakui School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653807

This paper presents a numerical study on six-degree-of-freedom (6-DOF) VIM response of a tethered round platform with strake under conditions of different cable lengths, mass ratios and center of gravity height ratios. The responses of amplitude and frequency were analyzed in detail. In addition, the vortex shapes under different parameters were studied. A numerical method based on solving Reynolds-averaged Navier-Stokes (RANS) equations with the SST k– Ε turbulence model is used in this study. The results show that the trajectory of the towing point presents a "figure 8 shape". The vertical motion amplitude is most affected in the range of parameters applied in this paper. When the cable length increases by 25%, the vertical motion amplitude is increased by 4 times. There is more than one dominant frequency with the increase of the cable length. The calculated results lay a foundation for studying the method of suppressing vortex-induced motion of underwater mooring platform. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Mooring

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Numerical Investigations of Seakeeping Performances of KCS in Head Waves Using Viscous/Hybrid Models 33rd

Numerical Investigations of Seakeeping Performances of KCS i...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Wu, Shiqi Yu, Jiawei Zou, Yanlin Yao, Chaobang Zhang, Zhiguo School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653807

This paper describes URANS and SWENSE simulations to determine the seakeeping performances of a container ship KCS in head waves. SWENSE is a hybrid approach of potential and viscous flows based on the functional decomposition model, where the total field is composed of the incident field and complementary field. Four wavelengths of regular head waves are considered according to the benchmark cases. Seakeeping performances of KCS in head waves using different wavegeneration methods are evaluated. Numerical accuracy of CFD results is investigated against EFD data. The comparison of the simulation results, computational requirements and efficiency of the URANS and hybrid methods is carried out. It is found that the SWENSE model has the almost same computational accuracy as the boundary wavegeneration approach, which is more time-saving and cost-saving for ship seakeeping prediction. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Seakeeping

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Numerical Study on The Effect of Water Depth on Roll Natural Period and Damping Coefficient of DTC in Shallow Water Regions 33rd

Numerical Study on The Effect of Water Depth on Roll Natural...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Chen, Jingyao Li, Jianxin Yu, Jiawei Liu, Liwei Zhang, Zhiguo School of Naval Architecture & Ocean Engineering Huazhong University of Science and Technology Key Laboratory of Ship and Ocean Hydrodynamics of Hubei Province Hubei Wuhan China

ISBN: (纸本)9781880653807

With the gradual large-scale of ships, some navigational areas can no longer be regarded as deep water but shallow water. The hydrodynamic performance of ships in shallow water is significantly different from that in deep water. Therefore, it is of great significance to study the roll motion of ships in shallow water and analyze the influence of water depth. In this study, the container ship model DTC (Duisburg Test Case) is selected as the computational model and the numerical simulations are conducted at different water depths. The simulation results of different water depth conditions are compared in detail to investigate the effect of water depth on roll natural period and damping coefficient and the cause of the change. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Damping

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