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Calculation Methods of Added Resistance and Ship Motion Response Based on Potential Flow and Viscous Flow theory

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China Ocean Engineering 2022年第3期36卷 488-499页

作者： WU Qi-ming ZHANG Bao-ji Shanghai Maritime University College of Ocean Science and EngineeringShanghai 201306China

To improve the energy efficiency of ships and to predict ship motion response under actual sea conditions,the far-field theory,strip theory,and Fujii and Takahashi’s modified semi-empirical method are based and studied to calculate the wave-induced added ***,a new modified formula based on the Maruo method is presented to calculate the radiation added resistance for the ship with a complex ***,some calculation details such as the Green function,the shape of the sections(shape below the still water level or shape below the wave level)in the strip theory,and so on are ***,the CFD method is used to simulate the motions of the hull and the added resistance,and the results of the CFD method and those of other numerical methods are analyzed and compared with the experiment *** modified method in the paper can predict the added resistance in waves for the complex-hull-surface ships well and quickly.

关键词： wave-induced added resistance strip theory computation fluid dynamics motion response

Investigation of rotor–stator interaction broadband noise using a RANS-informed analytical method

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Chinese Journal of Aeronautics 2021年第10期34卷 53-66页

作者： Hang TONG Lin LI Liangfeng WANG Luqin MAO Weiyang QIAO School of Power and Energy NorthwesternPolytechnical UniversityXi'an 710129China High Speed Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

A Reynolds-Averaged Navier Stokes(RANS)-information analytical method for predicting Rotor-Stator Interaction(RSI)broadband noise is established in this ***,the turbulence information is deduced from RANS simulation ***,the unsteady load on the stator blade is calculated using a strip theory approach based on LINearized SUBsonic unsteady flow in cascade(LINSUB)and 2-D equivalence *** the end,the sound power of RSI broadband noise is calculated by coupling the unsteady load on the stator blade with acoustic analogy and annular duct *** broadband noise model part of the RANS-information analytical method is validated against the upstream sound power of an annular cascade experimental ***,the RANS-information analytical method is used in predicting RSI broadband noise of a single-stage axial fan acoustic experimental bench,the results illustrate that the RANS-information analytical method can accurately predict the RSI broadband noise in different fan working *** simplification the Wave Leading Edge(WLE)stator blade,the effect of WLE stator blade on RSI broadband noise is *** the simplification may bring some discrepancies,the results illustrate that the RANS-information analytical method has the capability for further studies on the broadband noise reduction with WLE stator blade.

关键词： Acoustic analogy Analytical methods Rotor-stator interaction broadband noise strip theory Wavy leading edge

Numerical simulations of vortex-induced vibrations of a flexible riser with different aspect ratiosin uniform and shear currents

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Journal of Hydrodynamics 2017年第6期29卷 1010-1022页

作者：端木玉邹璐万德成 State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityCollaborative Innovation Center Jor Advanced Ship and Deep-Sea ExplorationShanghai 200240China Guangzhou Maritime University Guangzhou 510725China

This paper aimed at describing numerical simulations of vortex-induced vibrations（VIVs） of a long flexible riser with different length-to-diameter ratio（aspect ratio） in uniform and shear currents. Three aspect ratios were simulated： L/D= 500, 750 and 1 000. The simulation was carried out by the in-house computational fluid dynamics（CFD） solver viv-FOAM-SJTU developed by the authors, which was coupled with the strip method and developed on the OpenFOAM platform. Moreover, the radial basis function（RBF） dynamic grid technique is applied to the viv-FOAM-SJTU solver to simulate the VIV in both in-line（IL） and cross-flow（CF） directions of flexible riser with high aspect ratio. The validation of the benchmark case has been completed. With the same parameters, the aspect ratio shows a significant influence on VIV of a long flexible riser. The increase of aspect ratio exerted a strong effect on the IL equilibrium position of the riser while producing little effect on the curvature of riser. With the aspect ratio rose from 500 to 1 000, the maximum IL mean displacement increased from 3 times the diameter to 8 times the diameter. On the other hand, the vibration mode of the riser would increase with the increase of aspect ratio. When the aspect ratio was 500, the CF vibration was shown as a standing wave with a 3-（rd） order single mode. When the aspect ratio was 1 000, the modal weights of the 5-（th） and 6-（th） modes are high, serving as the dominant modes. The effect of the flow profile on the oscillating mode becomes more and more apparent when the aspect ratio is high, and the dominant mode of riser in shear flow is usually higher than that in uniform flow. When the aspect ratio was 750, the CF oscillations in both uniform flow and shear flow showed multi-mode vibration of the 4-（th） and 5-（th） mode. While, the dominant mode in uniform flow is the 4-（th） order, and the dominant mode in shear flow is the 5-（th） order.

关键词： Vortex-induced vibration (VIV) flexible riser radial basis function interpolation strip theory viv-FOAM-SJTU solver

Hydrodynamic Coefficients and Wave Excitation Forces for A Ship near A Quay

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海洋工程：英文版 2004年第1期18卷 119-128页

作者： M. Hasan Adil 段文洋 College of Shipbuilding Engineering

In this paper, the effects of a quay or a solid jetty on hydrodynamic coefficients and vertical wave excitation forces on a ship with or without forward speed are discussed. A modified simple Green function technique is used to calculate the 2D coefficients while the strip theory is used to calculate the 3D coefficients. Wave excitation forces are also calculated with the strip theory. Numerical results are provided for hydrodynamic coefficients and vertical wave excitation forces on a 200 000 DWT tanker ship. It is found that the quay has a considerable effect on the hydrodynamic coefficients and wave excitation forces for a ship.

关键词： hydrodynamic coefficients Green function technique strip theory quay jetty

Modeling of Multi-Freedom Ship Motions in Irregular Waves with Fuzzy Neural Networks

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海洋工程：英文版 2003年第2期17卷 255-264页

作者：余建星陆培毅高喜峰夏锦祝 School of Civil Engineering Tianjin University

In this paper, the neural network technology is combined with the fuzzy set theory to model the wave-induced ship motions in irregular seas. This combination makes possible the handling of a non-linear dynamic system with insufficient input information. The numerical results from the strip theory are used to train the networks and to demonstrate the validity of the proposed procedure.

关键词： strip theory ship motions neural network fuzzy logic system modeling

Effective Estimation for UAV Propeller Performance

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第5期32卷 502-507页

作者：刘莉施商涛张晓辉郭昌伟 School of Aerospace Engineering Beijing Institute of Technology

A new effective propeller performance estimation method is employed to calculate the propeller performance in the preliminary design of unmanned aerial vehicles(UAVs).The propeller three-dimensional aerodynamic characteristics leading to the blade tip vortices are considered to improve the blade element *** rule of the airfoil lift coefficient is summarized to enhance the calculation speed and the universality of this ***,wind tunnel test data of the propellers are used to verify the correctness of the *** error is less than9%,which is accurate enough in the preliminary design of *** analysis is carried out with the variable empirical parameters,and the values of which only have slight influence on the calculated *** with the strip theory,the proposed method avoids a very high number of iterations and complicated ***,only a few measurable data are needed to get a relatively accurate *** calculation examples demonstrate excellent effectiveness in obtaining the propeller performance to improve the design of UAVs.

关键词： propellers strip theory preliminary design of UAVs blade tip effect

Application of Method of Fundamental Solutions in Solving Potential Flow Problems for Ship Motion Prediction

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Journal of Shanghai Jiaotong university(Science) 2013年第2期18卷 153-158页

作者：封培元马宁顾解忡 School of Naval Architecture Ocean and Civil EngineeringShanghai Jiaotong University State Key Laboratory of Ocean Engineering Shanghai Jiaotong University

A novel panel-free approach based on the method of fundamental solutions (MFS) is proposed to solve the potential flow for predicting ship motion responses in the frequency domain according to strip theory. Compared with the conventional boundary element method (BEM), MFS is a desingularized, panel-free and integration-free approach. As a result, it is mathematically simple and easy for programming. The velocity potential is described by radial basis function (RBF) approximations and any degree of continuity of the velocity potential gradient can be obtained. Desingularization is achieved through collating singularities on a pseudo boundary outside the real fluid domain. Practical implementation and numerical characteristics of the MFS for solving the potential flow problem concerning ship hydrodynamics are elaborated through the computation of a 2D rectangular section. Then, the current method is further integrated with frequency domain strip theory to predict the heave and pitch responses of a containership and a very large crude carrier (VLCC) in regular head waves. The results of both ships agree well with the 3D frequency domain panel method and experimental data. Thus, the correctness and usefulness of the proposed approach are proved. We hope that this paper will serve as a motivation for other researchers to apply the MFS to various challenging problems in the field of ship hydrodynamics.

关键词： method of fundamental solutions (MFS) panel-free strip theory ship hydrodynamics