Modeling of Flow-Induced Vibrations in Heat Exchangers and Nuclear Reactors

1974 ◽  
Vol 96 (4) ◽  
pp. 358-364 ◽  
Author(s):  
G. S. Beavers ◽  
R. Plunkett
Keyword(s):  
Reynolds Number ◽  
Heat Exchangers ◽  
Single Phase ◽  
Nuclear Reactors ◽  
Cross Flow ◽  
Flow Region ◽  
Light Water ◽  
Excited Vibration ◽  
Flow Induced Vibrations ◽  
High Reynolds

This paper discusses the appropriate scaling factors for the modeling of the fluid-mechanical interaction of complex structures. The possible mechanisms of flow-excited vibration are described, and scaling parameters are derived from considerations of the mechanical and fluid systems. The paper is particularly concerned with the flow-induced vibrations of banks of cylinders in single phase, high Reynolds number, turbulent, cross flow, as occur for example in light water nuclear reactors and heat exchangers. It is concluded that the modeling of the tube banks in light water nuclear reactors will involve a mismatch of Reynolds number, but that the major phenomena of fluid-solid interaction in the single-phase flow region will probably be closely replicated if the Reynolds number is high enough so that the entering flow is turbulent and if the scaling ratio is not too large.

Fine Structure of Vortex Sheet Rollup by Viscous and Inviscid Simulation

1991 ◽  
Vol 113 (1) ◽  
pp. 31-36 ◽  
Author(s):  
G. Tryggvason ◽  
W. J. A. Dahm ◽  
K. Sbeih
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Large Scale ◽  
Stokes Equations ◽  
Flow Region ◽  
Vortex Sheet ◽  
Navier Stokes ◽  
Vortex Sheets ◽  
Limiting Behavior ◽  
High Reynolds

Numerical simulations of the large amplitude stage of the Kelvin-Helmholtz instability of a relatively thin vorticity layer are discussed. At high Reynolds number, the effect of viscosity is commonly neglected and the thin layer is modeled as a vortex sheet separating one potential flow region from another. Since such vortex sheets are susceptible to a short wavelength instability, as well as singularity formation, it is necessary to provide an artificial “regularization” for long time calculations. We examine the effect of this regularization by comparing vortex sheet calculations with fully viscous finite difference calculations of the Navier-Stokes equations. In particular, we compare the limiting behavior of the viscous simulations for high Reynolds numbers and small initial layer thickness with the limiting solution for the roll-up of an inviscid vortex sheet. Results show that the inviscid regularization effectively reproduces many of the features associated with the thickness of viscous vorticity layers with increasing Reynolds number, though the simplified dynamics of the inviscid model allows it to accurately simulate only the large scale features of the vorticity field. Our results also show that the limiting solution of zero regularization for the inviscid model and high Reynolds number and zero initial thickness for the viscous simulations appear to be the same.

Further Investigation of Discharge Coefficient for PTC 6 Flow Nozzle in High Reynolds Number

2015 ◽  
Author(s):  
Noriyuki Furuichi ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
Kazuo Shibuya
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
High Reynolds Number ◽  
Discharge Coefficient ◽  
Flow Region ◽  
Number Range ◽  
Discharge Coefficients ◽  
Reynolds Number Range ◽  
High Reynolds

The discharge coefficients of the throat tap flow nozzle based on ASME PTC 6 are measured in wide Reynolds number range from Red=5.8×104 to Red=1.4×107. The nominal discharge coefficient (the discharge coefficient without tap) is determined from the discharge coefficients measured for different tap diameters. The tap effects are correctly obtained by subtracting the nominal discharge coefficient from the discharge coefficient measured. Finally, by combing the nominal discharge coefficient and the tap effect determined in three flow regions, that is, laminar, transitional and turbulent flow region, the new equations of the discharge coefficient are proposed in three flow regions.

Self-Excited Vibration of Cross-Shaped Tube Bundle in Cross Flow

2002 ◽  
Author(s):  
Fumio Inada ◽  
Takashi Nishihara ◽  
Akira Yasuo ◽  
Ryo Morita ◽  
Akihiro Sakashita ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Tube Bundle ◽  
Cross Flow ◽  
Small Scale ◽  
Design Guideline ◽  
Shaped Tube ◽  
Excited Vibration ◽  
Scale Test ◽  
Flexible Tubes

Cross-shaped tube bundle is proposed for a lower plenum structure in a next generation LWR. Vibration response of cross-shaped tube bundle in cross flow has been measured in water tunnel tests. First, small-scale test was conducted. Tests were conducted with 3×3 flexible tubes as well as single flexible tube in rigid tube bundle. The flexible tubes could vibrate in lift, drag, and torsional direction. The effect of arrangements of tube bundle and the natural frequency ratio of bending and torsional vibrations were considered. Second, a large-scale test was conducted for only one case to check the effect of Reynolds number, in which Reynolds number was 10 times larger than that of small-scale test. In all the cases, large amplitude vibration could appear when the flow velocity became larger than a critical value, and a self-excited vibration was found to occur. The nondimensional critical gap velocity of the large-scale test agreed well with that of the small-scale test, which suggested that the effect of Reynolds number was not so large. A design guideline to prevent self-excited vibration was proposed for cross-shaped tube bundle.

K-1229 Turbulence-Induced Fluid Dynamic Forces Acting on Cross-Shaped Tube Bundle in Cross Flow : Part 2 : Measurement in the High Reynolds Number

2001 ◽  
Vol V.01.1 (0) ◽  
pp. 139-140
Author(s):  
Takashi NISHIHARA ◽  
Nobukazu TANAKA ◽  
Fumio INADA ◽  
Akira YASUO ◽  
Shinichi KAWAMURA ◽  
...  
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Tube Bundle ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Shaped Tube ◽  
Dynamic Forces ◽  
Flow Part ◽  
High Reynolds

Prediction of the Damaging Flow-Induced Vibrations in Tubular Heat Exchangers With Triangular Arrays

2014 ◽  
Author(s):  
Yehia A. Khulief ◽  
Salem A. Bashmal ◽  
Sayed A. Said ◽  
Dhawi A. Al-Otaibi ◽  
Khalid M. Mansour
Keyword(s):  
Mathematical Model ◽  
Service Life ◽  
Test Section ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Test Rig ◽  
Flow Rates ◽  
Tube Arrays ◽  
Flow Induced Vibrations ◽  
The Mathematical Model

The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross-flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model developed in [1] for square tube arrays was extended and utilized to study the triangular tube patterns. A laboratory test rig with instrumented test section is used to measure the fluidelastic coefficients to be used for tuning the mathematical model. The test section can be made of any bundle pattern. In this study, two test sections were constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized in predicting the onset of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations; namely the square and rotated square arrays reported in [1]. The results of the four different tube patterns are viewed in the light of TEMA predictions. The comparison demonstrated that TEMA guidelines are more conservative in all configurations considered.

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