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Coupling of RANS and BEM Solvers for Simulation of Propeller Behind the Hull in Full Appended Model

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China Ocean Engineering 2024年第3期38卷 424-438页

作者： Saeed NAJAFI Mehdi POURMOSTAFA LIU Peng-fei Iranian National Institute for Oceanography and Atmospheric Science(INIOAS) Tehran 14155-4781Iran Department of Maritime Engineering Amir Kabir University of TechnologyTehran 15875-4413Iran Marine Offshore and Subsea TechnologySchool of EngineeringNewcastle UniversityNewcastle upon TyneNE17RUUK

To design a propeller for ship power plant,the interaction between ship hull and propeller must be taken into *** main concern is to apply the wake effect of ship stern on the propeller *** this paper,a coupled BEM(Boundary Element method)/RANS(Renolds-Averaged Navier−Stokes)solver is used to simulate propeller behind the hull in the self-propulsion *** motivation of this work is to develop a practical tool to design marine propulsion system without suffering long computational *** unsteady boundary element method which is also known as panel method is chosen to estimate the propeller *** wakes are treated using a time marching wake alignment ***,a RANS code coupled with VoF equation is developed to consider the ship motions and wake field effects in the problem.A coupling algorithm is developed to interchange ship wake field to the potential flow solver and propeller thrust to the RANS *** on the difference between hull resistance and the propeller thrust,a PI controller is developed to compute the propeller RPM in every time *** of the solver is carried out using the towing tank test report of a 50 m oceanography research *** factor and trust deduction coefficient are estimated ***,the wake rollup pattern of the propeller in open water is compared with the propeller in real wake field.

关键词： RANS BEM coupled method ship propeller self-propulsion wake sheet pattern

NEW TREATMENT OF ESSENTIAL BOUNDARY CONDITIONS IN EFG method BY COUPLING WITH RPIM

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Acta Mechanica Solida Sinica 2013年第3期26卷 302-316页

作者： Yang Cao Linquan Yao Yu Yin School of Mathematical Sciences Soochow University School of Urban Rail Transportation Soochow University

One of major difficulties in the implementation of meshfree methods using the mov- ing least square （MLS） approximation, such as element-free Galerkin method （EFG）, is the im- position of essential boundary conditions as the approximations do not pass through the nodal parameter values. Another class of meshfree methods based on the radial basis point interpola- tion can satisfy the essential boundary conditions exactly since its approximation function passes through each node in an influence domain and thus its shape functions possess the properties of delta function. In this paper, a coupled element-free Galerkin（EFG）-radial point interpola- tion method （RPIM） is proposed to enhance their advantages and avoid their disadvantages. Discretized equations of equilibrium are obtained in the RPIM region and the EFG region, respectively. Then a collocation approach is introduced to couple the RPIM and the EFG method. This method satisfies the linear consistency exactly and can maintain the stiffness matrix symmetric. Numerical tests show that this method gives reasonably accurate results consistent with the theory.

关键词： meshfree method moving least-squares (ntis) approximation radial point inter-polation method (rpim) coupled method collocation approach

Validation and application of three-dimensional discontinuous deformation analysis with tetrahedron finite element meshed block

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Acta Mechanica Sinica 2012年第6期28卷 1602-1616页

作者： Jun Liu Zheng Nan Ping Yi School of Hydraulic Engineering Dalian University of Technology School of Civil Engineering Dalian University of Technology

In the last decade, three dimensional discontin- uous deformation analyses （3D DDA） has attracted more and more attention of researchers and geotechnical engineers worldwide. The original DDA formulation utilizes a linear displacement function to describe the block movement and deformation, which would cause block expansion under rigid body rotation and thus limit its capability to model block de- formation. In this paper, 3D DDA is coupled with tetrahe- dron finite elements to tackle these two problems. Tetrahe- dron is the simplest in the 3D domain and makes it easy to implement automatic discretization, even for complex topol- ogy shape. Furthermore, element faces will remain planar and element edges will remain straight after deformation for tetrahedron finite elements and polyhedral contact detection schemes can be used directly. The matrices of equilibrium equations for this coupled method are given in detail and an effective contact searching algorithm is suggested. Valida- tion is conducted by comparing the results of the proposed coupled method with that of physical model tests using one of the most common failure modes, i.e., wedge failure. Most of the failure modes predicted by the coupled method agree with the physical model results except for 4 cases out of the total 65 cases. Finally, a complex rockslide example demon- strates the robustness and versatility of the coupled method.

关键词： Three-dimensional discontinuous deformation analysis Finite element method coupled method Valida-tion

Influence of coupled boundary layer suction and bowed blade on flow field and performance of a diffusion cascade

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Chinese Journal of Aeronautics 2017年第1期30卷 249-263页

作者： Cao Zhiyuan Liu Bo Zhang Ting Yang Xiqiong Chen Pingping College of Engineering Peking University School of Power and Energy Northwestern Polytechnical University AECC Xi’an Aero-engine Controls Co. LTD

Based on the investigation of mid-span local boundary layer suction and positive bowed cascade, a coupled local tailored boundary layer suction and positive bowed blade method is developed to improve the performance of a highly loaded diffusion cascade with less suction slot. The effectiveness of the coupled method under different inlet boundary layers is also *** show that mid-span local boundary layer suction can effectively remove trailing edge separation, but deteriorate the flow fields near the endwall. The positive bowed cascade is beneficial for reducing open corner separation, but is detrimental to mid-span flow fields. The coupled method can further improve the performance and flow field of the cascade. The mid-span trailing edge separation and open corner separation are eliminated. Compared with linear cascade with suction, the coupled method reduces overall loss of the cascade by 31.4% at most. The mid-span loss of the cascade decreases as the suction coefficient increases, but increases as bow angle increases. The endwall loss increases as the suction coefficient increases. By contrast, the endwall loss decreases significantly as the bow angle increases. The endwall loss of coupled controlled cascade is higher than that of bowed cascade with the same bow angle because of the spanwise inverse ‘‘C＂ shaped static pressure distribution. Under different inlet boundary layer conditions, the coupled method can also improve the cascade effectively.

关键词： Axial compressor Boundary layer suction Bowed blade Corner separation coupled method Passage vortex

Flutter analyses of complete aircraft based on hybrid grids and parallel computing

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Science China(Technological Sciences) 2013年第2期56卷 398-404页

作者： ZHENG GuanNan YANG GuoWei QIAN Wei Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences Shenyang Aircraft Design and Research Institute

A tightly coupled method was developed to analyse aeroelasticity by constructing subiterative schemes for fluid and structural equations of motion,*** MPI partition parallel computing,the fluid was solved by Navier-Stokes equations based on hybrid grids.A new unstructured background grid deformtion method was used for the CFD grid *** transonic flutter wind tunnel model of a complete aircraft was simulated to validate the developed *** flutter characteristics of the aircraft was analysed and compared with the test *** indicates that the devoloped method has a relatively higher precision and can be used for aeronautical engineering application.

关键词： CFD CSD aeroelasticity coupled method flutter MPI

Full time-domain nonlinear coupled dynamic analysis of a truss spar and its mooring/riser system in irregular wave

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Science China(Physics,Mechanics & Astronomy) 2014年第1期57卷 152-165页

作者： YANG MinDong TENG Bin XIAO LongFei NING DeZhi SHI ZhongMin QU Yan Guangdong Electric Power Design Institute China Energy Engineering Group Co. Ltd. Department of Ocean Engineering Ocean University of China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Technology Research Department China National Offshore Oil Corporation

A new full time-domain nonlinear coupled method has been established and then applied to predict the responses of a Truss Spar in irregular wave. For the coupled analysis, a second-order time-domain approach is developed to calculate the wave forces, and a finite element model based on rod theory is established in three dimensions in a global coordinate system. In nu- merical implementation, the higher-order boundary element method （HOBEM） is employed to solve the velocity potential, and the 4th-order Adams-Bashforth-Moultn scheme is used to update the second-order wave surface. In deriving convergent solu- tions, the hull displacements and mooring tensions are kept consistent at the fairlead and the motion equations of platform and mooring-lines/risers are solved simultaneously using Newmark-fl integration scheme including Newton-Raphson iteration. Both the coupled quasi-static analysis and the coupled dynamic analysis are performed. The numerical simulation results are also compared with the model test results, and they coincide very well as a whole. The slow-drift responses can be clearly ob- served in the time histories of displacements and mooring tensions. Some important characteristics of the coupled responses are concluded.

关键词： coupled method full time-domain second-order truss spar rod theory irregular wave

Research on the Initial Ignition of the Underwater Launching Solid Rocket Motor

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Journal of Beijing Institute of Technology 2010年第4期19卷 422-426页

作者：马艳丽姜毅郝继光刘伯伟 School of Aerospace Engineering Beijing Institute of Technology

The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket *** MIXTURE multiple-phase model was set to simulate the initial *** water vaporization was researched and the energy transfer was added to the energy *** flow field and the vaporization were calculated *** initial ignition process of the underwater solid rocket motor is obtained and the vaporization influence to the underwater launching is *** ＂neck＂,＂inverted jet＂ and ＂eruption＂ phenomenon of the bubble are *** bubble increases more rapidly because the steam mass added to the *** temperature is lower considering the vaporization because the steam enthalpy is lower than the fuel enthalpy and the flow field of the initial ignition of the underwater-launching solid rocket motor is accordant well to the reference.

关键词： solid rocket motor underwater launching multiple phases flow vaporization coupled method

THE BEM FOR SOLVING THE NONHOMOGFNEOUS HELMHOLTZ EQUATION WITH VARIABLE COEFFICIENTS

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Applied Mathematics and Mechanics(English Edition) 1996年第1期17卷 84-89页

作者：王守信刘喜平彭天国赵忠生赵素华

Considering the fundamental solution of the Laplace equation as the weight function,we give the iterative format for solving the nonhomogeneous Helmholtz equation with variable coefficients. Furthermore, the iteration method of BEM for solving the equation mentioned above is obtained. The numerical example is given in this paper. Finally, the iteration method of BUM mentioned above is compared with the coupled method of BEM that was presented before then by authors.

关键词： Helmholtz equation iteration method coupled method