scholarly journals Low-frequency modes in the fluid-structure interaction of a U-tube model for the steam generator in a PWR

2019 ◽  
Vol 51 (4) ◽  
pp. 1008-1016 ◽  
Author(s):  
Hao Zhang ◽  
Se-Myong Chang ◽  
Soong-Hyun Kang
Keyword(s):  
Steam Generator ◽  
Fluid Structure Interaction ◽  
Low Frequency ◽  
Tube Model ◽  
Fluid Structure ◽  
Structure Interaction

Simulation of Fluid Flow Using Reduced-Order Modeling by POD Approach Applied to a Fixed Tube Bundle System

2010 ◽  
Author(s):  
Marie Pomarede ◽  
Erwan Liberge ◽  
Aziz Hamdouni ◽  
Elisabeth Longatte ◽  
Jean-Franc¸ois Sigrist
Keyword(s):  
Dynamic Analysis ◽  
Steam Generator ◽  
Tube Bundle ◽  
Fluid Structure Interaction ◽  
Reduced Model ◽  
Steam Generator Tube ◽  
Fluid Structure ◽  
Reduced Order ◽  
Structure Interaction ◽  
Tube Bundles

Tube bundles in steam boilers of nuclear power plants and nuclear on-board stokehold are known to be exposed to high levels of vibrations. This coupled fluid-structure problem is very complex to numerically set up, because of its three-dimensional characteristics and because of the large number of degrees of freedom involved. A complete numerical resolution of such a problem is currently not viable, all the more so as a precise understanding of this system behaviour needs a large amount of data, obtained by very expensive calculations. We propose here to apply the now classical reduced order method called Proper Orthogonal Decomposition to a case of 2D flow around a tube bundle. Such a case is simpler than a complete steam generator tube bundle; however, it allows observing the POD projection behaviour in order to project its application on a more realistic case. The choice of POD leads to reduced calculation times and could eventually allow parametrical investigations thanks to a low data quantity. But, it implies several challenges inherent to the fluid-structure characteristic of the problem. Previous works on the dynamic analysis of steam generator tube bundles already provided interesting results in the case of quiescent fluid [J.F. Sigrist, D. Broc; Dynamic Analysis of a Steam Generator Tube Bundle with Fluid-Structure Interaction; Pressure Vessel and Piping, July 27–31, 2008, Chicago]. Within the framework of the present study, the implementation of POD in academic cases (one-dimensional equations, 2D-single tube configuration) is presented. Then, firsts POD modes for a 2D tube bundle configuration is considered; the corresponding reduced model obtained thanks to a Galerkin projection on POD modes is finally presented. The fixed case is first studied; future work will concern the fluid-structure interaction problem. Present study recalls the efficiency of the reduced model to reproduce similar problems from a unique data set for various configurations as well as the efficiency of the reduction for simple cases. Results on the velocity flow-field obtained thanks to the reduced-order model computation are encouraging for future works of fluid-structure interaction and 3D cases.

Low Frequency Piezoelectric Synthetic Jets

2010 ◽  
Author(s):  
Charles E. Seeley ◽  
Mehmet Arik ◽  
Yogen Uttukar ◽  
Tunc Icoz
Keyword(s):  
Low Cost ◽  
Heated Surface ◽  
Fluid Structure Interaction ◽  
Low Frequency ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Active Cooling ◽  
Compact Size

Active cooling is often required for circuit boards with high heat generation densities. Synthetic jets driven with piezoelectric actuators offer interesting capabilities for localized active cooling of electronics due to their compact size, low cost and substantial cooling effectiveness. The design of synthetic jets for specific applications requires practical design tools that capture the strong fluid structure interaction without long run times. There is particular interest in synthetic jets that have a low operating frequency to reduce noise levels. This paper describes how common finite element (FE) and computational fluid dynamics (CFD) codes can be used to calculate parameters for a synthetic jet fluid structure interaction (FSI) model that only requires a limited number of degrees of freedom and is solved using a direct approach for low frequency synthetic jets. Tests are performed based on impinging on a heated surface to measure heat transfer enhancement. The test results are compared to the FSI model results for validation and agreement is found to be good in the frequency range of interest from 200 to 500 Hz.

A Perturbation Method for Low-Frequency Fluid-Structure Interaction Problems

1973 ◽  
Vol 40 (2) ◽  
pp. 388-394 ◽  
Author(s):  
Y. K. Lou
Keyword(s):  
Wave Equation ◽  
Perturbation Method ◽  
Electromagnetic Scattering ◽  
Perturbation Methods ◽  
Separation Of Variables ◽  
Fluid Structure Interaction ◽  
Low Frequency ◽  
Approximate Solutions ◽  
Fluid Structure ◽  
Structure Interaction

Perturbation methods have been used for electromagnetic scattering and diffraction problems in recent years. A similar method suitable for low-frequency fluid-structure interaction problems is presented. The essence of the method lies in the fact that approximate solutions for fluid-structure interaction problems can be obtained from a set of Poisson’s equations, rather than from the reduced wave equation. The method is particularly useful for those problems where the Poisson’s equation may be solved by the method of separation of variables while the reduced wave equation cannot. As an illustrative example, the vibrations of a submerged spherical shell is studied using the perturbation method and the accuracy of the method is demonstrated.

WALL SHEAR STRESSES IN A FLUID–STRUCTURE INTERACTION MODEL OF PULSE WAVE PROPAGATION

2014 ◽  
Vol 14 (02) ◽  
pp. 1450019 ◽  
Author(s):  
FAN HE
Keyword(s):  
Wave Propagation ◽  
Pulse Wave ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Elastic Tube ◽  
Tube Model ◽  
Pulse Wave Propagation ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Internal Radius

In our prior paper, a fluid–structure interaction model of pulse wave propagation, called the elastic tube model, has been developed. The focus of this paper is wall shear stress (WSS) in this model and the effects of different parameters, including rigid walls, wall thickness, and internal radius. The unsteady flow was assumed to be laminar, Newtonian and incompressible, and the vessel wall to be linear-elastic isotropic, and incompressible. A fluid–structure interaction scheme is constructed using a finite element method. The results demonstrate the elastic tube plays an important role in WSS distributions of wave propagation. It is shown that there is a time delay between the WSS waveforms at different locations in the elastic tube model while the time delay cannot be observed clearly in the rigid tube model. Compared with the elastic tube model, the increase of the wall thickness makes disturbed WSS distributions, however WSS values are increased greatly due to the decrease of the internal radius. The results indicate that the effects of different parameters on WSS distributions are significant. The proposed model gives valid results.

Research on Fluid-Structure Interaction Dynamic Characteristics of Steam Generator Heat Exchanger Tubes

2012 ◽  
Vol 482-484 ◽  
pp. 183-187
Author(s):  
Li Na Zhang ◽  
Hui Zhao ◽  
Min Shan Liu
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Steam Generator ◽  
Dynamic Characteristics ◽  
Fluid Structure Interaction ◽  
Heat Exchanger Tube ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Steam Generator Tubes ◽  
Exchanger Tube

For heat exchanger tube of steam generator, the relation between heat exchanger tube and fluid is typical fluid-structure interaction problem. Flow induced vibration has been found so far to be responsible for fatigue damage and failure of steam generator tubes, which will result in large economic loss and radioactive pollution. So the steam generator tubes are the weakest link in the primary coolant loop. Based on the synthesis of all sorts of factors influencing the dynamic characteristics of steam generator heat transfer tubes, establishing the heat transfer tube model, research on the weakening effect of fluid hole on fluid, the natural frequencies of the heat transfer tubes are analyzed under different fluid holes and fluid hole distance by numerical simulation.

Dynamic Analysis of a Steam Generator Tube Bundle With Fluid-Structure Interaction

2008 ◽  
Author(s):  
Jean-Franc¸ois Sigrist ◽  
Daniel Broc
Keyword(s):  
Dynamic Analysis ◽  
Steam Generator ◽  
Pressure Vessel ◽  
Tube Bundle ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Point Of View ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Structure Problem

The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid-structure interaction modelling. As the coupled fluid-structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled methods can not be applied for industrial studies. In the present case, the three-dimensional fluid-structure problem is solved with an homogenisation method, which has been previously exposed and successfully validated on a two-dimensional elementary tube bundle (J.F. Sigrist, D. Broc; Investigation of Numerical Methods for Modal Analysis of Tube Bundle with Fluid-Structure Interaction; Pressure Vessel and Piping, San Antonio, 22–26 July 2007). Formulation of the homogenisation method for general three-dimensional cases is exposed in the paper. Application to a simplified (however representative of an actual industrial nuclear component) steam generator is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid-structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the homogenisation method for periodic fluid-structure problems modelling.

Modal Analysis of a Nuclear Reactor With Fluid-Structure Interaction: Influence of Fluid Compressibility

2006 ◽  
Author(s):  
Jean-Franc¸ois Sigrist ◽  
Daniel Broc
Keyword(s):  
Modal Analysis ◽  
Compressible Fluid ◽  
Nuclear Reactor ◽  
Fluid Structure Interaction ◽  
Low Frequency ◽  
Operating Pressure ◽  
Fluid Structure ◽  
Displacement Potential ◽  
Structure Interaction ◽  
Temperature Conditions

The present paper deals with the modal analysis of a nuclear with fluid-structure interaction effects. In a previous study, added mass and added stiffness effects due to fluid-structure interaction were modeled and studied. A dynamic analysis was performed for a seismic excitation, i.e. in the low frequency range. The present study deals with high frequency analysis, i.e. taking into account compressibility effects in the fluid problem. Elasto-acoustic coupling phenomena are studied and described in the industrial case. The elasto-acoustic coupled problem is formulated using the displacement/pressure-displacement potential coupled formulation which yields symmetric matrices. A modal analysis is first performed on the fluid problem alone, with a calculation of acoustic eigenfrequencies and the corresponding modal masses. A modal analysis is then performed for the coupled fluid-structure problem in the case of an incompressible fluid and a compressible fluid at standard pressure and temperature conditions and for a compressible fluid at the operating pressure and temperature conditions. Elasto-coupling effects are then highlighted and discussed.

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