Papers by Keyword: Fluid Structure Interaction (FSI)

Abstract: The present work is aimed to free vibration characteristics of marine propeller in fluid, and analyze the influence of fluid inertial effect on propeller. The fully coupled three dimensional finite element method is applied, and the commercial finite element code, ANSYS WORKBENCH, has been used to perform modal analysis for both wet and dry configurations via fluid-structure interaction APDL commands for secondary development. On this basis, analyze a marine propeller in air and in fluid with finite element analysis, then the differences of natural vibration frequencies and vibration modes of the propeller for different boundary conditions are discussed. In addition, the natural frequencies curves are presented. Results show that the natural frequencies of propeller in fluid are significantly lower than those in air, the fluid inertia effect also has some influences on vibration mode.

Abstract: The oscillating flow is an important factor affecting the performance of the rotor–seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the self-excited vibration, which is induced by interaction between the unstable seal fluid flow and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear model with the flow induced vibration.

Abstract: This paper analyzes the vortex induced vibration (VIV) phenomena of twin box bridge girders by means of 2D computational fluid dynamics (CFD) models. The modeling of turbulence follows a methodology known as large eddy simulation (LES) in which the large scales of turbulence are resolved, while the small ones are modeled by means of sub-grid-models. The dynamic response of structure in relation to the fluid is solved by embedding the code of Newmark-β method in user defined functions of Fluent. The time history of girder’s vibration displacement is obtained successfully, which agrees well with the experiment results of wind tunnel tests. “Lock-in”, “beat” phenomena and the displacement “detuning” phenomena in the locked field are also gained.

Abstract: As the excavation of tunnels, there are new channels of the groundwater drainage. The original supply of the circulatory system has been destroyed. The effects of groundwater to rock mass of surrounding rock are aggravated. In this paper, combined with a new highway tunnel project, the model is built according to the design parameters and the site engineering geological conditions of the tunnel. The fluid-structure interaction module of the finite difference software FLAC3D is used for the research on tunnel excavation. The distribution of seepage field, the stability of surrounding rock and rock deformation under saturated conditions during the tunnel excavation have been analyzed. The simulation results have certain guiding meaning on fracture development, the stability design of tunnels in water-rich stratum and the design and construction of anti-drainage.

Abstract: This paper proposed a numerical approach called improved FE-BE (finite element-boundary element) method to solve the fluid-structure interaction problems of plate-like systems. In order to avoid the mesh of both faces of the thin plates, some dumb structures were added to make the plate systems closed. Thus the conventional FE-BE method can be adopted to solve this problem. The dynamic response equation of the inner region can be obtained by the FE method, and the acoustic added mass and damping coefficients of the exterior region can be obtained by the BE method. Then the final fluid-structure interaction equation can be easily solved. Numerical results of some examples are computed to demonstrate the validation of the present method. The comparison of numerical results and reference solutions shows that the proposed method is acceptable for solving the fluid-structure interaction of plates.

Abstract: The stress distribution and modal characteristics of a space inflatable torus is investigated using the nonlinear finite element method. This paper focused on the effect of enclosed air on the modal analysis of the torus, including the effect of follower pressure load and the effect of the interaction between the enclosed air and the torus structure. Research shows that follower pressure stiffness significantly reduces the natural frequencies and changes mode shapes order. The fluid-structure interaction obviously reduces the natural frequencies, and the in-plane translation mode is observed. Follower pressure stiffness has no effect on the in-plane translation mode. Fluid-structure interaction decreases the natural frequencies of the modal considering the follower load effect, but it does not change mode shapes order. The effect of enclosed gas seriously reduces the natural frequencies, changes mode shapes order, and produces the in-plane translation mode.

Abstract: Ground-supported cylindrical tanks are used to store a variety of liquids. The fluid was develops a hydrodynamic pressures on walls and bottom of the tank during earthquake. This paper provides dynamic time-history response of concrete open top cylindrical liquid storage tank considering fluid-structure interaction due to earthquake. Numerical model of cylindrical tank was performed by application of the Finite Element Method (FEM) utilizing software ADINA. Arbitrary-Lagrangian-Eulerian (ALE) formulation was used for the problem analysis. Two way Fluid-Structure Interaction (FSI) techniques were used for the simulation of the interaction between the structure and the fluid at the common boundary

Abstract: The oscillating flow is an important factor affecting the performance of the rotor–seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the self-excited vibration, which is induced by interaction between the unstable seal fluid flow and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear model with the flow induced vibration.

Abstract: A numerical approach is carried out to investigate the dynamic behavior of the CFRP strengthened pressure pipes subjected to impact load. In the FE analyses, Johnson-cook model is used to simulate metal subjected to large plastic strains and high strain rates, the fluid and pipe interaction is modeled by the surface-based fluid cavity to include the coupling effect between the deformation of the pipe and the internal pressure. Besides, the Hashin damage model is used to predict the damage of CFRP. The objectives of the numerical simulations are to capture the measured forming and crash history of the CFRP strengthened pressure pipes and gain an insight into the dynamic behavior of CFRP strengthened pressure pipes subject to impact load. The effects of internal pressure and the thickness of the CFRP are investigated, providing a detailed understanding of parameter sensitivity.

Abstract: Submarine pipelines are described as the lifeblood of offshore oil and it is crucial to ensure the seismic safety of the submarine pipelines. Based on the fluid-structure interaction numerical analysis method and by using finite element software ADINA, the analysis models of the free long-span submarine flexible pipelines under earthquakes were established. By employing dynamic time-history method, the influences of fluid-structure interaction on the seismic response of the submarine pipelines were researched. The results showed that the peak normal stress and the peak displacement of submarine pipelines’ mid-span considering the influences of the fluid-structure interaction are greater than those without considering the influences, and the influences of the fluid-structure interaction on the seismic response of the submarine pipelines will increase with the increase of the submarine pipelines‘ diameter.