Flow-Induced Vibration and Noise in Tube-Bank Heat Exchangers Due to von Karman Streets

1968 ◽  
Vol 90 (1) ◽  
pp. 134-146 ◽  
Author(s):  
Y. N. Chen
Keyword(s):  
Wind Tunnel ◽  
Vortex Shedding ◽  
Heat Exchangers ◽  
Flow Induced Vibration ◽  
Tube Bank ◽  
Von Karman ◽  
Von Kármán Streets ◽  
Von Kármán

This paper treats the problem of vibration and noise in tube-bank heat exchangers. The frequency of vortex shedding has been investigated by many authors, and their results have varied considerably. The author, in previous works, correlated these different data into a curve group of his own, and now proceeds to further analyze the problem. Results of experiments performed in a small wind tunnel are given, accompanied by typical graphs. Based on his findings, the author concludes with some design proposals for suppressing vibrations.

Prevention and Cure of Flow-Induced Vibration Problems in Tubular Heat Exchangers

1980 ◽  
Vol 102 (2) ◽  
pp. 138-145 ◽  
Author(s):  
F. L. Eisinger
Keyword(s):  
Heat Exchangers ◽  
Cross Flow ◽  
Acoustic Vibration ◽  
New Method ◽  
Flow Induced Vibration ◽  
Tube Bank ◽  
Vibration Resistance ◽  
Stability Diagrams ◽  
Vibration Problems ◽  
Prevention And Cure

Various methods for predicting and solving tube and acoustic vibration problems in heat exchangers in cross flow are presented: the use of stability diagrams comprising in-service experience of heat exchangers, for a general multispan tube model; a method of selecting efficient baffle configurations for prevention of acoustic vibration, a new method of fin barriers, an alternative to conventional baffling; a new method of enhancing the vibration resistance of a tube bank based on the use of a helical spacer; these methods, singly or in combination, can be used to design against flow-induced vibration.

Cavitation Influence on von Kármán Vortex Shedding and Induced Hydrofoil Vibrations

2007 ◽  
Vol 129 (8) ◽  
pp. 966-973 ◽  
Author(s):  
Philippe Ausoni ◽  
Mohamed Farhat ◽  
Xavier Escaler ◽  
Eduard Egusquiza ◽  
François Avellan
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Trailing Edge ◽  
Cavitation Inception ◽  
Structure Interaction ◽  
New Correlation ◽  
Von Karman ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency ◽  
Von Kármán

The present study deals with the shedding process of the von Kármán vortices at the trailing edge of a 2D hydrofoil at high Reynolds number Reh=25×103–65×103. This research focuses mainly on the effects of cavitation and fluid-structure interaction on the mechanism of the vortex generation. The vortex shedding frequency, derived from the flow-induced vibration measurement, is found to follow the Strouhal law provided that no hydrofoil resonance frequencies are excited, i.e., lock-off. For such a regime, the von Kármán vortices exhibit strong spanwise 3D instabilities and the cavitation inception index is linearly dependent on the square root of the Reynolds number. In the case of resonance, the vortex shedding frequency is locked onto the hydrofoil eigenfrequency and the spatial coherence is enhanced with a quasi-2D shape. The measurements of the hydrofoil wall velocity amplitude and phase reveal the first torsion eigenmotion. In this case, the cavitation inception index is found to be significantly increased compared to lock-off conditions. It makes clear that the vortex roll-up is amplified by the phase locked vibrations of the trailing edge. For the cavitation inception index, a new correlation relationship that encompasses the entire range of Reynolds numbers, including both the lock-off and the lock-in cases, is proposed and validated. In contrast to the earlier models, the new correlation takes into account the trailing edge displacement velocity. In addition, it is found that the transverse velocity of the trailing edge increases the vortex strength linearly. This effect is important in the context of the fluid-structure interaction, since it implies that the velocity of the hydrofoil trailing edge increases the fluctuating forces on the body. It is also demonstrated that cavitation developing in the vortex street cannot be considered as a passive agent for the turbulent wake flow. In fact, for fully developed cavitation, the vortex shedding frequency increases up to 15%, which is accompanied by the increase of the vortex advection velocity and reduction of the streamwise vortex spacing. In addition, a significant increase of the vortex-induced vibration level is found at cavitation onset. These effects are addressed and thought to be a result of the increase of the vorticity by cavitation.

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