Discussion: “Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 2—Lift Forces of Single Cylinders” (Chen, Y. N., 1972, ASME J. Eng. Ind., 94, pp. 613–618)

The trend of the fluctuating lift coefficient CL and the dimensionless shedding frequency S (Strouhal number) of the vortex in tube bundles at higher Reynolds numbers R will be predicted by the course of the steady pressure drag coefficient CD at the corresponding R ranges. Furthermore, some measurements of the vortex lift forces in tube bundles will be given. It reveals that the lift force for certain small transverse tube spacings possesses a strong second harmonic. The tubes and, therefore, the transverse gas column in the tube bundle channel can be excited to vibrate in resonance either at the critical flow velocity or at its half value. Finally, the coupled vibration between the vortex shedding and the transverse gas column will be covered with some experiments.

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Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 2—Lift Forces of Single Cylinders

Journal of Engineering for Industry ◽

10.1115/1.3428209 ◽

1972 ◽

Vol 94 (2) ◽

pp. 613-618 ◽

Cited By ~ 8

Author(s):

Y. N. Chen

Keyword(s):

Lift Coefficient ◽

Vortex Street ◽

Circular Cylinders ◽

Pressure Drag ◽

Vortex Streets ◽

Order Of Magnitude ◽

Karman Vortex ◽

Lift Forces ◽

The Right ◽

Right Order

The fluctuating lift force of the Karman vortex on a single circular cylinder will be investigated theoretically for an ideal inviscid vortex street with rectilinear vortices. In this investigation the model introduced by von Karman will be used. As a result, the relationship between the fluctuating lift coefficient CL and the characteristic dimensions of the vortex street can be derived. This leads to establishing the equation between the fluctuating lift coefficient CL and the steady pressure drag coefficient CD. Since the curve of the theoretical lift coefficient practically envelops the spreading field of the experimentally determined points, the theory can be considered to be adequate to give the right order of magnitude for the lift of the Karman vortex. It will further be shown, that the spread of the measured values is in connection with the correlation length of the vortex along the cylinder axis.

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Vortex- and Wake-Induced Vibrations of a Circular Cylinder Placed in the Proximity of Two Fixed Cylinders

Journal of Vibration Engineering & Technologies ◽

10.1007/s42417-021-00430-7 ◽

2022 ◽

Author(s):

Yoshiki Nishi ◽

Yuga Shigeyoshi

Keyword(s):

Circular Cylinder ◽

Water Channel ◽

High Amplitude ◽

Circular Cylinders ◽

Circulating Water ◽

Vortex Induced Vibrations ◽

Vortex Streets ◽

Cylinder Model ◽

Karman Vortex ◽

Second Peak

Abstract Purpose This study aims to understand the vibratory response of a circular cylinder placed in proximity to other fixed bodies. Methods A circular cylinder model was placed in a circulating water channel and was supported elastically to vibrate in the water. Another two circular cylinders were fixed upstream of the vibrating cylinder. The temporal displacement variations of the vibrating cylinder were measured and processed by a frequency analysis. Results When the inline spacings were small, two amplitude peaks appeared in the reduced velocity range 3.0–13.0. When the inline spacings were large, the amplitude response showed a single peak. Conclusion For small inline spacings, the first peak was attributed to high-amplitude vibrations forced by Karman vortex streets shed from the upstream cylinders. The second peak arose from interactions of the wakes of the upstream cylinder with the vibrating cylinder. When the inline spacing increased, the vortex-induced vibrations resembled those of an isolated cylinder.

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Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 1—The Vortex Street Geometry of the Single Circular Cylinder

Journal of Engineering for Industry ◽

10.1115/1.3428206 ◽

1972 ◽

Vol 94 (2) ◽

pp. 603-610 ◽

Cited By ~ 13

Author(s):

Y. N. Chen

Keyword(s):

Reynolds Number ◽

Strouhal Number ◽

Vortex Street ◽

Circular Cylinders ◽

Number Range ◽

Pressure Drag ◽

Minimum Drag ◽

Vortex Streets ◽

Karman Vortex ◽

Better Than

The geometry of the vortex street for single circular cylinders will be calculated from the measured values given by numerous investigators about the steady pressure drag coefficient and the Strouhal number, whereby the Kronauer minimum drag criterion comes into use. The calculated results will be compared with the experimentally determined ones. A good agreement can be achieved between both. The Bearman-Strouhal number SB = fh/Us will also be computed as a function of the Reynolds number. Furthermore a new wake number C = fh2/Γ will be introduced. It will be shown that this new number is universally much better than the Bearman one. It remains constant at 0.165 for an ideal flow over the whole Reynolds number range up to the highest value of 107 ever measured hitherto.

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