Fluid-Structure Interaction of Stirrers in Mixing Vessels: Part I — Development of the Mechanical Model

2002 ◽  
Author(s):  
Michael Fischer ◽  
Klaus Strohmeier
Keyword(s):  
Fluid Structure Interaction ◽  
Life Time ◽  
Coupled Analysis ◽  
Major Influence ◽  
Integration Scheme ◽  
Two Phase ◽  
Structural Dynamic ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Analytical Formulae

Mixing stirrers are subject to severe damages when the rotational speed approaches the Eigenfrequency. Damping due to fluid-structure interaction between the mixing stirrer and the fluid in the vessel has major influence on the Eigenfrequency. Therefore coupled analysis of the flow field within a mixing vessel and the structural dynamic response of the stirrer should be conducted in order to evaluate vibrational amplitudes to guarantee life time safety for the stirrer. In some previous works at our institute CFD analysis of mixing stirrers has been carried out for both one-phase and two-phase flow. In this paper a simplified numerical model based on Newmark’s integration scheme is developed for the stirrer dynamics that is suitable to be implemented in the CFD code as a user subroutine. Results in terms of Eigenfrequencies are compared to results of analytical formulae and FEM results and show excellent agreement. In the second part of the paper the fully fluid-structure coupled analysis is presented (Part II).

Fluid-Structure Interaction of Stirrers in Mixing Vessels

2003 ◽  
Vol 125 (4) ◽  
pp. 440-445 ◽  
Author(s):  
Thomas Berger ◽  
Michael Fischer ◽  
Klaus Strohmeier
Keyword(s):  
Analytical Data ◽  
Fluid Structure Interaction ◽  
Life Time ◽  
Coupled Analysis ◽  
Major Influence ◽  
Integration Scheme ◽  
Structural Dynamic ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Analytical Formulas

Mixing stirrers are subject to severe damages when the rotational speed approaches the Eigenfrequency. Because of resonant vibrations, the stirrer deflection approaches infinity in the no damping case. Damping due to fluid-structure interaction between the mixing stirrer and the fluid in the vessel has major influence on the Eigenfrequency. Coupled analysis of the flow field within a mixing vessel and the structural dynamic response of the stirrer is necessary in order to evaluate vibrational amplitudes to guarantee life time safety for the stirrer. A simplified numerical model based on Newmark’s integration scheme is developed for the stirrer dynamics that is suitable to be implemented in a CFD code as a user subroutine. Results in terms of Eigenfrequencies are compared to results of analytical formulas and FEM results and show excellent agreement. The fully fluid-structure coupled analysis is also presented. As a new aspect, a rotating grid (sliding mesh) was combined with a deformable grid to simulate the impeller movement. The results are compared to experimental and analytical data and show good agreement.

scholarly journals Coupling Analysis of Fluid-Structure Interaction and Flow Erosion of Gas-Solid Flow in Elbow Pipe

2014 ◽  
Vol 6 ◽  
pp. 815945 ◽  
Author(s):  
Hongjun Zhu ◽  
Hongnan Zhao ◽  
Qian Pan ◽  
Xue Li
Keyword(s):  
Erosion Rate ◽  
Structural Changes ◽  
Fluid Structure Interaction ◽  
Fluid Phase ◽  
Diameter Ratio ◽  
Pipe Diameter ◽  
Discrete Phase Model ◽  
Two Phase ◽  
Fluid Structure ◽  
Structure Interaction

A numerical simulation has been conducted to investigate flow erosion and pipe deformation of elbow in gas-solid two-phase flow. The motion of the continuous fluid phase is captured based on calculating three-dimensional Reynolds-averaged-Navier-Stokes (RANS) equations, while the kinematics and trajectory of the discrete particles are evaluated by discrete phase model (DPM), and a fluid-structure interaction (FSI) computational model is adopted to calculate the pipe deformation. The effects of inlet velocity, pipe diameter, and the ratio of curvature and diameter on flow feature, erosion rate, and deformation of elbow are analyzed based on a series of numerical simulations. The numerical results show that flow field, erosion rate, and deformation of elbow are all sensitive to the structural changes and inlet condition changes. Higher inlet rate, smaller curvature diameter ratio, or smaller pipe diameter leads to greater deformation, while slower inlet rate, larger curvature diameter ratio, and larger pipe diameter can weaken flow erosion.

scholarly journals Linear Stability Analysis and Validation of a Unified Solution Method for Fluid-Structure-Interaction on Structural Dynamic Problems

2005 ◽  
Author(s):  
C. G. Giannopapa ◽  
G. Papadakis
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Solution Method ◽  
Fluid Structure Interaction ◽  
Analytic Solutions ◽  
Computational Domain ◽  
Structural Dynamic ◽  
Fluid Structure ◽  
Structure Interaction

In the conventional approach for fluid-structure interaction problems, the fluid and solid components are treated separately and information is exchanged across their interface. According to the conventional terminology, the current numerical methods can be grouped in two major categories: Partitioned methods and monolithic methods. Both methods use two separate sets of equations for fluid and solid. A unified solution method has been presented [1], which is different from these methods. The new method treats both fluid and solid as a single continuum, thus the whole computational domain is treated as one entity discretised on a single grid. Its behavior is described by a single set of equations, which are solved fully implicitly. In this paper, 2 time marching and one spatial discretisation scheme, widely used for fluids’ equations, are applied for the solution of the equations for solids. Using linear stability analysis, the accuracy and dissipation characteristics of the resulting difference equations are examined. The aforementioned schemes are applied to a transient structural problem (beam bending) and the results compare favorably with available analytic solutions and are consistent with the conclusions of the stability analysis. A parametric investigation using different meshes, time steps and beam sizes is also presented. For all cases examined the numerical solution was stable and robust and proved to be suitable for the next stage of application to full fluid-structure interaction problems.

scholarly journals Inflatable Leading Edge-Based Dynamic Stall Control considering Fluid-Structure Interaction

2020 ◽  
Vol 2020 ◽  
pp. 1-28
Author(s):  
Shi-Long Xing ◽  
He-Yong Xu ◽  
Ming-Sheng Ma ◽  
Zheng-Yin Ye
Keyword(s):  
Lift Coefficient ◽  
Fluid Structure Interaction ◽  
Leading Edge ◽  
Dynamic Stall ◽  
Elastic Membrane ◽  
Radius Of Curvature ◽  
Structural Dynamic ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Stall Control

The inflatable leading edge (ILE) is explored as a dynamic stall control concept. A fluid-structure interaction (FSI) numerical method for the elastic membrane structure is constructed based on unsteady Reynolds-averaged Navier-Stokes (URANS) and a mass-spring-damper (MSD) structural dynamic model. Radial basis function- (RBF-) based mesh deformation algorithm and Laplacian and optimization-based mesh smoothing algorithm are adopted in flowfield simulations to achieve the pitching oscillation of the airfoil and to ensure the mesh quality. An airfoil is considered at a freestream Mach number of 0.3 and chord-based Reynolds number of 3.92×106. The airfoil is pitched about its quarter-chord axis at a sinusoidal motion. The numerical results indicate that the ILE can change the radius of curvature of the airfoil leading edge, which could reduce the streamwise adverse pressure gradient and suppress the formation of dynamic stall vortex (DSV). Although the maximum lift coefficient of the airfoil is slightly reduced during the control process, the maximum drag and pitching moment coefficients of the airfoil are greatly reduced by up to 66% and 75.2%, respectively. The relative position of the ILE has a significant influence on its control effect. The control laws of inflation and deflation also affect the control ability of the ILE.

Explicit and Implicit Code Coupling Schemes in Fluid Structure Interaction

2005 ◽  
Author(s):  
E. Longatte ◽  
Z. Bendjeddou ◽  
V. Verreman ◽  
M. Souli
Keyword(s):  
Fluid Structure Interaction ◽  
Time Integration ◽  
Good Choice ◽  
Integration Scheme ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Interaction Field ◽  
Analytical Test ◽  
Time Integration Scheme ◽  
Implicit Code

In multi-physics numerical computations a good choice of code coupling schemes is required. Several methods are possible like: an explicit synchronous scheme an Euler implicit method and no interpolation on velocity pressure; an explicit asynchonous scheme using a Crank-Nicholson time integration scheme and interpolation on velocity and pressure; an implicit scheme using a fixed iterative method. In the present paper these different schemes are compared for application in fluid structure interaction field. In the first part numerical coupling schemes are presented. Then their capability to ensure energy conservation is discussed according to numerical results obtained in analytical test cases. Finally application of coupling process to fluid structure interaction problems is investigated and results are discussed in terms of added mass and damping induced by a fluid for a structure vibrating in fluid at rest.

Strength Analysis of Oil Tanker Under Numerical Wave

2018 ◽  
Author(s):  
Cheng Shu ◽  
Li Hong ◽  
Zhang Dongxu
Keyword(s):  
Structural Strength ◽  
Fluid Structure Interaction ◽  
Ocean Waves ◽  
Wave Action ◽  
Stokes Wave ◽  
Strength Analysis ◽  
Two Phase ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Equivalent Load

The strength of an oil carrier is generally checked using static load or equivalent load of wave action in accordance with relevant specifications. In order to accurately calculate the stress and the deformation of an oil carrier under wave action, the fluid-structure interaction system in the platform Workbench is used in this work. And, the pressure-based solver, the two-phase flow model and UDF (User Defined Function) in the software FLUENT are used to compile the three-order Stokes Wave so as to simulate ocean waves. Forces acting on the surface of the oil carrier are obtained by calculating the flow field, and the structural strength of the carrier is then investigated under sagging and hogging conditions. The results show that: the three-order Stokes Wave matches well with the theoretical result, and it is feasible to research the strength of the oil carrier by generating waves using this numerical method. In addition, the method of fluid-structure interaction is applied to investigate the structural strength of the fully-loaded carrier under sagging and hogging conditions.

A Qualified Method for Fluid-Structure Interaction in Piping Design

2006 ◽  
Author(s):  
Miks Hartmann
Keyword(s):  
Fluid Structure Interaction ◽  
Substantial Contribution ◽  
Structural Dynamic ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Fluid Forces ◽  
Various Boundary Conditions ◽  
Coupled Calculation ◽  
Piping Systems ◽  
Hydraulic Load

In piping design hydraulic load cases and the resulting dynamic structural loads are induced and generated by strongly time dependent pressure surges and subsequent oscillations. Therefore, with liquid filled piping, the implementation of fluid-structure interaction by coupling the fluiddynamic and the structural dynamic codes gives a substantial contribution to more realistic loading results. Considering this effect, usually a load reduction due to energy losses and the phase and frequency shift from fluid to structure and vice versa is achieved. In cases of fluid structure resonance the results are more reliable and can help to develop an optimized support concept. To realize the coupled calculation of both codes they are bundled by a special user environment, where the coupling points are specified and marked. We describe the input of fluid forces at those points and the treatment of the liquid masses inside the piping, as well as the method of back-coupling the resulting structural displacements into the fluid calculation. The method was validated against measurements of load cases in power plant piping systems and experimental results for various boundary conditions. The most realistic results were obtained by combining the coupling with the application of dynamic friction in the fluid code.

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