Study on In-Flow Vibration of Cylinder Arrays Caused by Cross Flow

2011 ◽  
Author(s):  
Tomomichi Nakamura ◽  
Keisuke Nishimura ◽  
Yoshiaki Fujita ◽  
Chihiro Kohara
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Cross Flow ◽  
Thin Plates ◽  
Streamwise Direction ◽  
Number Range ◽  
Direction Transverse ◽  
Drag Forces ◽  
Cylinder Arrays ◽  
Reynolds Number Range

The authors have studied the in-flow vibration phenomena of cylinder arrays caused by cross-flow in the low Reynolds number range around Re=800. This Reynolds number range has been studied because it is the range where symmetric vortex shedding occurs. This report is our first trial to study the in-line fluidelastic vibration of cylinder arrays. In initial tests, the flow velocity was increased up to the maximum achievable level by the test equipment. However, it was found that the array’s cantilever tube supports resulted in large static tube deflections due to static drag forces. The cylinder array tube supports have therefore been replaced by thin plates supported at both ends. The cylinders are set to be flexible both in the streamwise direction and the direction transverse to the flow. The obtained results of these two patterns are also compared with previous cantilevered data. The origin of the observed vibrations whether a self-induced mechanism or vortex shedding is discussed in detail.

Vortex shedding from a circular cylinder in moderate-Reynolds-number shear flow

1980 ◽  
Vol 101 (4) ◽  
pp. 721-735 ◽  
Author(s):  
Masaru Kiya ◽  
Hisataka Tamura ◽  
Mikio Arie
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Transverse Velocity ◽  
Number Range ◽  
Uniform Shear ◽  
Reynolds Number Range ◽  
Moderate Reynolds Number ◽  
Shear Parameter

The frequency of vortex shedding from a circular cylinder in a uniform shear flow and the flow patterns around it were experimentally investigated. The Reynolds number Re, which was defined in terms of the cylinder diameter and the approaching velocity at its centre, ranged from 35 to 1500. The shear parameter, which is the transverse velocity gradient of the shear flow non-dimensionalized by the above two quantities, was varied from 0 to 0·25. The critical Reynolds number beyond which vortex shedding from the cylinder occurred was found to be higher than that for a uniform stream and increased approximately linearly with increasing shear parameter when it was larger than about 0·06. In the Reynolds-number range 43 < Re < 220, the vortex shedding disappeared for sufficiently large shear parameters. Moreover, in the Reynolds-number range 100 < Re < 1000, the Strouhal number increased as the shear parameter increased beyond about 0·1.

On vortex shedding from a circular cylinder in the critical Reynolds number régime

1969 ◽  
Vol 37 (3) ◽  
pp. 577-585 ◽  
Author(s):  
P. W. Bearman
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Critical Reynolds Number ◽  
Narrow Band ◽  
Critical Regime ◽  
Number Range ◽  
Velocity Fluctuations ◽  
Reynolds Number Range

The flow around a circular cylinder has been examined over the Reynolds number range 105 to 7·5 × 105, Reynolds number being based on cylinder diameter. Narrow-band vortex shedding has been observed up to a Reynolds number of 5·5 × 105, i.e. well into the critical régime. At this Reynolds number the Strouhal number reached the unusually high value of 0·46. Spectra of the velocity fluctuations measured in the wake are presented for several values of Reynolds number.

Hydrodynamic Force Measurements on a Circular Cylinder Fitted With Peripheral Control Cylinders: Preliminary Results on the Development of VIV Suppressors

2015 ◽  
Author(s):  
Mariana Silva-Ortega ◽  
Gustavo R. S. Assi ◽  
Murilo M. Cicolin
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Vortex Shedding ◽  
Hydrodynamic Force ◽  
Force Measurements ◽  
Number Range ◽  
Preliminary Results ◽  
Reynolds Number Range

Recent achievements in controlling the boundary layer by moving surfaces have been encouraging the development and investigation of passive suppressors of vortex-induced vibration. Within this context, the main purpose of the present work is to evaluate the suppression of vortex shedding of a plain cylinder surrounded by two, four and eight smaller control cylinders. Experiments have been carried out on a fixed circular cylinder to investigate the effect of the control cylinders over drag reduction. Control cylinders with diameter of d/D = 0.06 were tested, where D is the diameter of the main cylinder. The gap between the main cylinder and the control cylinders varied between G/D = 0.05 and 0.15. Experiments with a plain cylinder in the Reynolds number range from 5,000 to 50,000 have been performed to serve as reference. It was found that a cylinder fitted with four control cylinders presented less drag and fluctuating lift than cylinders fitted with two or eight small cylinders.

Vortex shedding behind a square cylinder in transonic flows

1987 ◽  
Vol 178 ◽  
pp. 303-323 ◽  
Author(s):  
Takeo Nakagawa
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Shock Waves ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Acoustic Waves ◽  
Strong Shock ◽  
Square Cylinder ◽  
Number Range ◽  
Reynolds Number Range

This paper is primarily concerned with Mach-number effects on the vortex shedding behind a square cylinder (side length D = 20 mm) in a Reynolds-number range of 0.696 × 105 < Re < 4.137 × 105, and a Mach-number range of 0.1522 < M < 0.9049.Regular periodic vortex shedding is present, irrespective of the appearance of shock waves around a square cylinder. The shape of the vortices is, however, deformed by the shock waves, and each vortex centre becomes non-uniform while the vortex passes through the gap between the upper and lower shock waves. Weak shock waves around the square cylinder do not alter the Strouhal number, but strong shock waves weaken the vortex shedding and increase the Strouhal number suddenly. Acoustic waves have been recorded by the Mach-Zehnder interferometer when the Mach number is close to the critical value. The acoustic waves are generated most strongly at the instant when each vortex hits the foot of the shock waves formed above and below the vortex formation region.From the present work and that of Okajima (1982), it is suggested that the Strouhal number of alternating vortices shed from a square cylinder can be estimated to be about 0.13 in the Reynolds-number range between 102 and 3.4 × 105.

Friction Factor Measurements in an Equally Spaced Triangular Array of Circular Tubes

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Peter Vassallo ◽  
Paul Symolon
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Test Data ◽  
Tube Bundle ◽  
Cross Flow ◽  
Outer Diameter ◽  
Number Range ◽  
New Correlation ◽  
Reynolds Number Range ◽  
Factor Data

Friction factor data for adiabatic cross flow of water in a staggered tube array were obtained over a Reynolds number range (based on hydraulic diameter and gap velocity) of about 10,000–250,000. The tubes were 12.7mm(0.5in.) outer diameter in a uniformly spaced triangular arrangement with a pitch-to-diameter ratio of 1.5. The friction factor was compared to several literature correlations and was found to be best matched by the Idelchik correlation. Other correlations were found to significantly vary from the test data. Based on the test data, a new correlation is proposed for this tube bundle geometry, which covers the entire Reynolds number range tested.

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