scholarly journals Study on Fluid-Structure Coupling Vibration of Compressor Pipeline

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Jia Wu ◽  
Chunjie Li ◽  
Shuiying Zheng ◽  
Jingheng Gao
Keyword(s):  
Natural Frequencies ◽  
Actual Situation ◽  
Time Step ◽  
Coupling Vibration ◽  
Fluid Structure ◽  
Practical Engineering ◽  
Grid Nodes ◽  
Pipeline Vibration ◽  
Fifth Order ◽  
The Given

In practical engineering, pipeline vibration is often not caused by a single factor but by a combination of many factors. A fluid-structure coupling method is proposed in this paper and used to study the vibration of the compressor pipeline under the interaction of pipeline structure and airflow in it. The method is based on structured grids, so that the displacements of grid nodes can be calculated accurately at each time step. The results of transient calculation show that when the given inlet mass flow rate is constant and there is no other disturbance, the pressure fluctuation and the vibration of pipeline structure will occur by using fluid-structure coupling, and the vibration frequencies are consistent with the third- and fifth-order structural natural frequencies. Moreover, the higher the pressure in the pipe, the greater the fluid-structure coupling vibration. In addition, the fluid-structure coupling vibration not only occurs in the studied pipeline but also propagates to distant downstream pipeline. Comparing the above results with experimental results, it is found that the results of fluid-structure coupling calculation are in agreement with the actual situation, which shows that the method is reasonable and reliable and can be applied to engineering.

scholarly journals Analysis of Fluid–Structure Coupling Vibration Mechanism for Subsea Tree PipelineCombined with Fluent and Ansys Workbench

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 955
Author(s):  
Gongxing Wu ◽  
Xiaolong Zhao ◽  
Danda Shi ◽  
Xiaodong Wu
Keyword(s):  
Flow Field ◽  
Tree Model ◽  
Coupling Vibration ◽  
Fluid Structure ◽  
Variable Diameter ◽  
Safe Production ◽  
Oil Exploitation ◽  
Vibration Mechanism ◽  
The Given ◽  
Ansys Workbench

In the process of oil exploitation, subseatrees sometimes vibrate. In this paper, fluid–structure coupling software was used to study the causes of subsea tree vibration. First, the complex subsea tree model wassimplified, and ageometric grid model wasestablished for software calculation. Then, under the given two working conditions, the software Fluent wasused to analyze the pressure and velocity distribution of the subsea tree pipeline’s flow field. It was found that the pressure of the flow field changed greatly at the variable diameter and right-angles. Using Ansys Workbench software, flow-structure coupling calculations and modal analysis of the subsea tree werecarried out. The results showed that the vibration of the long straight pipeline section wassevere. Finally, the paper puts forward the measures to reduce the vibration of subsea tree pipelines and provides construction advice for the safe production of subsea trees.

Design Aspects of Nonlinear Vibration Analysis of Rectangular Orthotropic Membranes

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Robert Wetherhold ◽  
Punit S. Padliya
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Natural Frequencies ◽  
Design Parameters ◽  
Physical Parameters ◽  
Membrane Thickness ◽  
Time Step ◽  
Efficient Manner ◽  
Element Simulation ◽  
The Given

The natural frequencies of a specially orthotropic rectangular membrane are examined with respect to its design parameters. A method is presented for inferring the initial tensions from measured vibration frequencies and the sensitivity of the tensions with respect to imprecision in the measured frequencies is demonstrated. A sensitivity analysis is used to define the key design parameters, where relatively small changes in those parameters lead to large changes in the natural frequency. This analysis is useful in two senses: It permits the design to be rapidly changed in an efficient manner, and it indicates the physical parameters that must be closely controlled in order to achieve the desired frequency. The results of the theoretical analysis were compared with a finite element simulation using Abaqus for validation. The comparison showed that results were in close agreement up to an initial displacement magnitude-to-membrane thickness ratio (T0/h) value of about 25 for the given values of design parameters. This shows the limit of applicability of the analytical solution since the finite element (FE) simulation is fully updated at each time step with precision not available from the analytical solution.

A new dynamic mesh algorithm for studying the 3D transient flow field of tilting pad journal bearings

2016 ◽  
Vol 230 (12) ◽  
pp. 1470-1482 ◽  
Author(s):  
Mengxuan Li ◽  
Chaohua Gu ◽  
Xiaohong Pan ◽  
Shuiying Zheng ◽  
Qiang Li
Keyword(s):  
Flow Field ◽  
Equilibrium Position ◽  
Transient Flow ◽  
Journal Bearings ◽  
Dynamic Mesh ◽  
Static Equilibrium ◽  
Time Step ◽  
Tilting Pad ◽  
Grid Nodes ◽  
Tilting Pad Journal Bearings

A new dynamic mesh algorithm is developed in this paper to realize the three-dimensional (3D) computational fluid dynamics (CFD) method for studying the small clearance transient flow field of tilting pad journal bearings (TPJBs). It is based on a structured grid, ensuring that the total number and the topology relationship of the grid nodes remain unchanged during the dynamic mesh updating process. The displacements of the grid nodes can be precisely recalculated at every time step. The updated mesh maintains high quality and is suitable for transient calculation of large journal displacement in FLUENT. The calculation results, such as the static equilibrium position and the dynamic characteristic coefficients, are consistent with the two-dimensional (2D) solution of the Reynolds equation. Furthermore, in the process of transient analysis, under conditions in which the journal is away from the static equilibrium position, evident differences appear between linearized and transient oil film forces, indicating that the nonlinear transient calculation is more suitable for studying the rotor-bearing system.

scholarly journals Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

2018 ◽  
Vol 5 (2) ◽  
pp. 171717 ◽  
Author(s):  
Srivatsa Bhat K ◽  
Ranjan Ganguli
Keyword(s):  
Boundary Condition ◽  
Cross Section ◽  
Natural Frequencies ◽  
Rectangular Cross Section ◽  
Beam Equation ◽  
The Finite Element Method ◽  
Rayleigh Beam ◽  
Uniform Beam ◽  
Governing Differential Equation ◽  
The Given

In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

A Fast and Rigorously Parallel Surface Voxelization Technique for GPU-Accelerated CFD Simulations

2015 ◽  
Vol 17 (5) ◽  
pp. 1246-1270 ◽  
Author(s):  
C. F. Janßen ◽  
N. Koliha ◽  
T. Rung
Keyword(s):  
Graphics Processing Units ◽  
Parallel Implementation ◽  
Parallel Execution ◽  
Time Step ◽  
Cfd Simulations ◽  
Performance Loss ◽  
Neighbor Search ◽  
Body Shell ◽  
Normal Vectors ◽  
Grid Nodes

AbstractThis paper presents a fast surface voxelization technique for the mapping of tessellated triangular surface meshes to uniform and structured grids that provide a basis for CFD simulations with the lattice Boltzmann method (LBM). The core algorithm is optimized for massively parallel execution on graphics processing units (GPUs) and is based on a unique dissection of the inner body shell. This unique definition necessitates a topology based neighbor search as a preprocessing step, but also enables parallel implementation. More specifically, normal vectors of adjacent triangular tessellations are used to construct half-angles that clearly separate the per-triangle regions. For each triangle, the grid nodes inside the axis-aligned bounding box (AABB) are tested for their distance to the triangle in question and for certain well-defined relative angles. The performance of the presented grid generation procedure is superior to the performance of the GPU-accelerated flow field computations per time step which allows efficient fluid-structure interaction simulations, without noticeable performance loss due to the dynamic grid update.

Dynamic Analysis of the Joined-Wing Configuration in High-Altitude Long-Endurance Aircraft Using Fluid-Structure Interaction Model

2007 ◽  
Author(s):  
Prabu Ganesh Ravindren ◽  
Kirti Ghia ◽  
Urmila Ghia
Keyword(s):  
Finite Element ◽  
High Altitude ◽  
Fluid Structure Interaction ◽  
Structural Deformation ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Joined Wing ◽  
Long Endurance

Recent studies of the joined-wing configuration of the High Altitude Long Endurance (HALE) aircraft have been performed by analyzing the aerodynamic and structural behaviors separately. In the present work, a fluid-structure interaction (FSI) analysis is performed, where the fluid pressure on the wing, and the corresponding non-linear structural deformation, are analyzed simultaneously using a finite-element matrix which couples both fluid and structural solution vectors. An unsteady, viscous flow past the high-aspect ratio wing causes it to undergo large deflections, thus changing the domain shape at each time step. The finite element software ANSYS 11.0 is used for the structural analysis and CFX 11.0 is used for the fluid analysis. The structural mesh of the semi-monocoque joined-wing consists of finite elements to model the skin panel, ribs and spars. Appropriate mass and stress distributions are applied across the joined-wing structure [Kaloyanova et al. (2005)], which has been optimized in order to reduce global and local buckling. The fluid region is meshed with very high mesh density at the fluid-structure interface and where flow separation is predicted across the joint of the wing. The FSI module uses a sequentially-coupled finite element equation, where the main coupling matrix utilizes the direction of the normal vector defined for each pair of coincident fluid and structural element faces at the interface [ANSYS 11.0 Documentation]. The k-omega turbulence model captures the fine-scale turbulence effects in the flow. An angle of attack of 12°, at a Mach number of 0.6 [Rangarajan et al. (2003)], is used in the simulation. A 1-way FSI analysis has been performed to verify the proper transfer of loads across the fluid-structure interface. The CFX pressure results on the wing were transferred across the comparatively coarser mesh on the structural surface. A maximum deflection of 16 ft is found at the wing tip with a calculated lift coefficient of 1.35. The results have been compared with the previous study and have proven to be highly accurate. This will be taken as the first step for the 2-way simulation. The effect of a coupled 2-way FSI analysis on the HALE aircraft joined wing configuration will be shown. The structural deformation history will be presented, showing the displacement of the joined-wing, along the wing span over a period of aerodynamic loading. The fluid-structure interface meshing and the convergence at each time step, based on the quantities transferred across the interface will also be discussed.

Fluid-Structure Interaction Approach for Numerical Investigation of a Flexible Hydrofoil Deformations in Turbulent Fluid Flow

2018 ◽  
Author(s):  
M. Benaouicha ◽  
S. Guillou ◽  
A. Santa Cruz ◽  
H. Trigui
Keyword(s):  
Fluid Flow ◽  
Numerical Model ◽  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Time Step ◽  
Fluid Structure ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Structure Interaction ◽  
Ale Formulation

The study deals with a 3D Fluid-Structure Interaction (FSI) numerical model of a rectangular cantilevered flexible hydrofoil subjected to a turbulent fluid flow regime. The structural response and dynamic deformations are studied by analyzing the oscillations frequencies and amplitudes, under a hydrodynamics loads. The obtained numerical results are confronted with experimental ones, for validation. The numerical model is performed in the same geometric, physical and material conditions as the experimental set-up carried out in a hydrodynamic tunnel. A polyacetal (POM) flexible hydrofoil NACA0015 with an angle of attack of 8° is considered to be immersed in a fluid flow at a Reynold number of 3 × 105. The structure is initially at rest and then moved by the action of the fluid flow. The numerical model is based on a strong coupling procedure for solving the Fluid-Structure Interaction problem. The Arbitrary Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equations is used and an anisotropic diffusion equation is solved to compute the fluid mesh velocity and position at each time step. The finite volume method is used for the numerical resolution of the fluid dynamics equations. The structure deformations are described by the linear elasticity equation which is solved by the finite elements method. The Fluid-Structure coupled problem is solved by using the partitioned FSI implicit algorithm. A good agreement between numerical and experimental results for the hydrodynamics coefficients and hydrofoil deformations, maximum deflection and frequencies is obtained. The added mass and damping are analyzed and then the FSI effect on the dynamic deformations of the structure is highlighted.

The Natural Frequencies of Free and Constrained Non-Uniform Beams

1960 ◽  
Vol 64 (599) ◽  
pp. 697-699 ◽  
Author(s):  
R. P. N. Jones ◽  
S. Mahalingam
Keyword(s):  
Degrees Of Freedom ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Normal Modes ◽  
Iteration Process ◽  
Conservative System ◽  
Basic System ◽  
Orthogonal Functions ◽  
Added Masses ◽  
The Given

The Rayleigh-Ritz method is well known as an approximate method of determining the natural frequencies of a conservative system, using a constrained deflection form. On the other hand, if a general deflection form (i.e. an unconstrained form) is used, the method provides a theoretically exact solution. An unconstrained form may be obtained by expressing the deflection as an expansion in terms of a suitable set of orthogonal functions, and in selecting such a set, it is convenient to use the known normal modes of a suitably chosen “ basic system.” The given system, whose vibration properties are to be determined, can then be regarded as a “ modified system,” which is derived from the basic system by a variation of mass and elasticity. A similar procedure has been applied to systems with a finite number of degrees of freedom. In the present note the method is applied to simple non-uniform beams, and to beams with added masses and constraints. A concise general solution is obtained, and an iteration process of obtaining a numerical solution is described.

Seismic Response Analysis of Liaocheng Guangyue Tower

2015 ◽  
Vol 744-746 ◽  
pp. 911-914
Author(s):  
Zhao Bo Meng ◽  
Guan Dong Qiao ◽  
Jie Jin
Keyword(s):  
Seismic Response ◽  
Soil Structure ◽  
Natural Frequencies ◽  
Timber Structure ◽  
Soil Structure Interaction ◽  
Response Analysis ◽  
Actual Situation ◽  
Seismic Response Analysis ◽  
Structure Interaction ◽  
Rare Earthquake

This paper establishes three models using ANSYS, which were timber structure of Guangyue Tower, timber structure-tower base and timber structure-tower base-foundation. The first 3 natural frequencies of timber structure respectively were 0.8524Hz、1.1273 Hz and 1.7426 Hz through modal analysis, which were compared with calculations from code. Lanzhou Wave was chosen to analyze the seismic response of Guangyue Tower, and the amplitudes were adjusted to 55gal and 310gal respectively according to the frequent earthquake and rare earthquake, which were inputted to the above models. As can be seen from the calculations, the maximum displacements of the three models were in the top nodes, and tower base had a greater impact on vibration of timber structure, which could not be ignored in seismic response analysis; considering soil-structure interaction in seismic response analysis could better reflect the actual situation of Guangyue Tower.

Simulation of Water Droplet Merging under Shock Wave Using Real Ghost Fluid Method

2013 ◽  
Vol 444-445 ◽  
pp. 628-632
Author(s):  
Ru Chao Shi ◽  
Sheng Li Xu ◽  
Ya Jun Zhang
Keyword(s):  
Shock Wave ◽  
Interpolation Method ◽  
Time Discretization ◽  
Problem Solver ◽  
Ghost Fluid Method ◽  
Numerical Accuracy ◽  
Air Water Interface ◽  
Fifth Order ◽  
The Given ◽  
Flow States

This paper presents a 3D numerical simulation of water droplets merging under a given shock wave. We couple interpolation method to RGFM (Real Ghost Fluid Method) to improve the numerical accuracy of RGFM. The flow states of air-water interface are calculated by ARPS (approximate Riemann problem solver). Flow field is solved by Euler equation with fifth-order WENO spatial discretization and fourth-order R-K (Runge-Kutta) time discretization. We also employ fifth-order HJ-WENO to discretize level set equation to keep track of gas-liquid interface. Numerical results demonstrate that droplets shape has little change before merging and the merged droplet gradually becomes umbrella-shaped under the given shock wave. We verify that combination of RGFM with interpolation method has the property of reducing numerical error by comparing to the results without employment of interpolation method.

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