The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 2—Criterion for the Fluidelastic Orbital Vibration of Tube Arrays

1974 ◽  
Vol 96 (3) ◽  
pp. 1065-1071
Author(s):  
Y. N. Chen
Keyword(s):  
High Speed ◽  
Vortex Formation ◽  
Vortex Pair ◽  
Free Shear Layer ◽  
Vortex Model ◽  
Speed Flow ◽  
Vortex Streets ◽  
Tube Arrays ◽  
Karman Vortex ◽  
Tube Banks

The phenomenon on the tubes in a tube row, which vibrate alternately along the row in the transverse and stream-wise directions, will be explained by a vortex model. This model consists of the symmetrical vortex pair trains behind the stream-wisely vibrating tubes, and the Karman vortex streets behind the transversely vibrating tubes. It will be shown in the paper that the coupling between these two groups of vortex systems can excite the tube arrays to perform this fluidelastic vibration. A criterion for the onset of this orbital movement will be given with the expression ξ = R/Sxt. This criterion predicts a strong fluidelastic vibration for tubes with low transverse tube spacings and low natural flexible frequencies in a high speed flow. The theory leading to this criterion is based on the phenomenon of the variation in the position of the separation point for the free shear layer during the cylinder vibration. A switching of the jet for maintaining the fluidelastic vibration is then a result of this variation.

Frequency of the Karman Vortex Streets in Tube Banks

1967 ◽  
Vol 71 (675) ◽  
pp. 211-214 ◽  
Author(s):  
Y. N. Chen
Keyword(s):  
Linear Relation ◽  
Heat Exchangers ◽  
Stream Velocity ◽  
Outer Diameter ◽  
Theoretical Justification ◽  
Flow Area ◽  
Vortex Streets ◽  
Transverse Distance ◽  
Karman Vortex ◽  
Tube Banks

In the note “Aerodynamically induced vibration in coolers”, by D. G. Mabey (pp 876-7, December 1965 Journal), the results of Grotz and Arnold concerning the frequency of the Karman vortex streets in tube banks, such as in heat exchangers, are mentioned, as is also the law of the linear relation between f(T—d)/V and (2T-L)/d, as found by Putnam, where f frequency of vortex sheddingT transverse distanceL longitudinal distance between tubesd outer diameter of tubeV mean stream velocity based on minimum flow area between the tubesThis linear relation has no theoretical justification and cannot be accurate, as is admitted by the author cited. A further investigation on a theoretical basis seems to be necessary.

Vortex Formation in the Wake of a Vibrating, Flexible Cable

1974 ◽  
Vol 96 (4) ◽  
pp. 317-322 ◽  
Author(s):  
S. E. Ramberg ◽  
O. M. Griffin
Keyword(s):  
Vortex Shedding ◽  
Vortex Formation ◽  
Reynolds Numbers ◽  
Hot Wire ◽  
Near Wake ◽  
Formation Region ◽  
Vortex Streets ◽  
Region Length ◽  
Karman Vortex ◽  
Flexible Cables

The von Karman vortex streets formed in the wakes of vibrating, flexible cables were studied using a hot-wire anemometer. All the experiments took place in the flow regime where the vibration and vortex-shedding frequencies lock together, or synchronize, to control the wake formation. Detailed measurements were made of the vortex formation flow for Reynolds numbers between 230 and 650. As in the case of vibrating cylinders, the formation-region length is dependent on a shedding parameter St* related to the natural Strouhal number and the vibrational conditions. Furthermore, the near wake configuration is found to be dependent on the local amplitude of vibration suggesting that the vibrating cylinder rseults are directly applicable in that region.

The vortex street in the wake of a vibrating cylinder

1972 ◽  
Vol 55 (1) ◽  
pp. 31-48 ◽  
Author(s):  
Owen M. Griffin ◽  
Charles W. Votaw
Keyword(s):  
Vortex Breakdown ◽  
Vortex Formation ◽  
Reynolds Numbers ◽  
Vortex Street ◽  
Fundamental Parameter ◽  
Formation Region ◽  
Von Karman ◽  
Vortex Streets ◽  
Karman Vortex ◽  
Von Kármán

The von Kármán vortex streets formed in the wakes of vibrating smooth cylinders and cables were studied using a hot-wire anemometer and flow visualization by fog injection in a wind tunnel. All the experiments took place in the flow regime where the vibration and vortex-shedding frequencies lock together, or synchronize, to control the formation of the wake. Since the flow in the vortex formation region is fundamental to further understanding of the interaction between a vibrating bluff obstacle and its wake, detailed measurements were made of the formation-region flow for Reynolds numbers between 120 and 350. The formationregion length is shown to be a fundamental parameter for the wake, and is dependent on a shedding parameterSt* related to the natureally occurring Strouhal number for the von Kármán street. The effects of vibration amplitude and frequency on the mean and fluctuating velocity fields in the wake become apparent when the downstream displacement is scaled with the formation length. The von Kármán vortex street behind a vibrating cylinder is divided into three predominant flow regimes: the formation, stable and unstable regions. Fundamental differences exist in the vortex streets generated behind stationary and vibrating cylinders, but many classical characteristics, including the manner of vortex breakdown in the unstable region, are shared by the two systems.

The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 1—The Interplay Between the Self-Excited Vibration of the Single Circular Cylinder and the Karman Vortex

1974 ◽  
Vol 96 (3) ◽  
pp. 1060-1064
Author(s):  
Y. N. Chen
Keyword(s):  
Vortex Shedding ◽  
Flow Model ◽  
Vortex Formation ◽  
The Self ◽  
Vortex Street ◽  
Excited Vibration ◽  
Karman Vortex ◽  
Tube Banks ◽  
Lock In ◽  
The Relationship

In the present paper a series of experimental results obtained by several authors on the phenomena of the vortex street behind a vibrating cylinder are analysed. From this we can establish a flow model for the relationship between the vortex shedding, the cylinder movement, the vortex lift and the variation in the position of the separation point. This relationship reveals that a close synchronization of the vortex shedding and the lift generated by it will arise when the flow velocity enters the lock-in region. Furthermore, the flow model will enable us to predict the narrowing of the vortex street shed by a vibrating cylinder for certain Reynolds number ranges. The theory can thus qualitatively explain the corresponding phenomena observed by Koopmann, Griffin and Votaw.

Excitation of Free Shear-Layer Instabilities for High-Speed Flow Control

AIAA Journal ◽  
2018 ◽  
Vol 56 (5) ◽  
pp. 1770-1791 ◽  
Author(s):  
Mo Samimy ◽  
Nathan Webb ◽  
Michael Crawley
Keyword(s):  
Flow Control ◽  
Shear Layer ◽  
High Speed ◽  
Free Shear Layer ◽  
High Speed Flow ◽  
Speed Flow

The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 3—Damping Capability of the Tube Bank Against Vortex-Excited Sonic Vibration in the Fluid Column

1974 ◽  
Vol 96 (3) ◽  
pp. 1072-1075 ◽  
Author(s):  
Y. N. Chen ◽  
W. C. Young
Keyword(s):  
Velocity Distribution ◽  
Vortex Formation ◽  
Tube Bank ◽  
Ideal Case ◽  
Vortex Streets ◽  
Boiler Units ◽  
Tube Banks ◽  
Damping Capability ◽  
Proper Consideration ◽  
The Ideal

The damping criterion previously proposed by Chen 1964/1968 is evaluated with respect to a series of existing units using various fuels. The critical value of this criterion, which was given by Chen as 600 for the ideal case with uniform velocity distribution, has been found to be about 2000 for the tube bank heat exchangers in boiler units. The reason for this difference appears to lie in the degree of uniformity of the velocity distribution over the streaming section. Since the velocity distribution in the boiler units cannot be uniform at all, the vortex streets formed in the tube bank will disturb each other. A large damping will thus arise. The damping criterion can thus be employed to design a sonic vibration-free tube bank through proper consideration of tube spacings, Reynolds number, and Strouhal number.

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