scholarly journals Cross Flow Through in Closely Arranged Circular Cylinders. 2nd Report. Influence of Longitudinal Spacing Ratio on Velocity Fluctuation of Cross Flow Through in The Tube Banks and Analyses of Linear Free Vibration.

1996 ◽  
Vol 62 (596) ◽  
pp. 1300-1306
Author(s):  
Tetsushi NAKAI ◽  
Kyozo AYUKAWA ◽  
Tsutomu INOUE
Keyword(s):  
Free Vibration ◽  
Velocity Fluctuation ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Spacing Ratio ◽  
Flow Through ◽  
Tube Banks

VORTEX INTERFERENCE IN THE WAKE OF TWO TANDEM CIRCULAR CYLINDERS IN A CROSS FLOW

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1595-1598 ◽  
Author(s):  
KAZUO OHMI ◽  
SUXIA LI ◽  
SEUNGHEE JEON ◽  
LINGYUN CHEN
Keyword(s):  
Reynolds Number ◽  
Image Analysis ◽  
Cross Correlation ◽  
Laser Sheet ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Water Tank ◽  
Cylinder Wake ◽  
Flow Reynolds Number ◽  
Spacing Ratio

The wake of two circular cylinders in tandem arrangement is investigated by flow visualization and PIV experiments in a towing water tank. The two cylinders are spaced at L/d (spacing ratio) = 2.0 to 15.0 and the cross flow Reynolds number ranges from 60 to 120. The flow is seeded with fine Rilsan particles and illuminated by a 2 mm thick laser sheet. The PIV image analysis is done by a standard cross correlation scheme with a powerful validation algorithm followed by multi-pass adaptive cross correlation iterations. The main objective of the study is to investigate the characteristics of the downstream cylinder wake changing considerably with the spacing ratio of the two cylinders.

Vorticity Shedding and Acoustic Resonance Excitation of Two Tandem Spirally Finned Cylinders in Cross-Flow

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Mohammed Alziadeh ◽  
Atef Mohany
Keyword(s):  
Reynolds Number ◽  
Strouhal Number ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Acoustic Resonance ◽  
Root Diameter ◽  
Circular Cylinders ◽  
Resonance Excitation ◽  
Equivalent Diameter ◽  
Spacing Ratio

Abstract The aeroacoustic response of two tandem spirally finned cylinders is experimentally investigated. Three different pairs of finned cylinders are studied with fin pitch-to-root diameter ratios (p/Dr) ranging between 0.37≤p/Dr≤0.74. The spiral fins are crimped similar to those used in industrial heat exchangers. The results of the finned cylinders are compared with bare, circular cylinders with a modified equivalent diameter (Deq). The spacing ratio (L/Deq) between the cylinders are kept constant at L/Deq=2.00. The Strouhal number (StDeq) of the tandem finned cylinders is found to be higher compared to the tandem bare cylinders, resulting in an earlier onset of coincidence resonance. Moreover, unlike the tandem bare cylinders, the Strouhal number of the finned cylinders did not depend on the Reynolds number, suggesting that the flow characteristics around the finned cylinders are unaffected by Reynolds number. Only the tandem finned cylinders with the lowest fin pitch-to-root diameter ratio (p/Dr=0.37) were capable of exciting precoincidence acoustic resonance. The precoincidence resonance mechanism is similar to that observed in in-line tube bundles.

The Hydrodynamic Stability of Couette-Poiseuille-Porous Annular Flow

1972 ◽  
Vol 39 (3) ◽  
pp. 840-842 ◽  
Author(s):  
J. M. Gersting
Keyword(s):  
Hydrodynamic Stability ◽  
Outer Cylinder ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Neutral Stability ◽  
Boundary Motion ◽  
Special Cases ◽  
Flow Through ◽  
Axisymmetric Disturbances ◽  
Small Disturbances

The linear hydrodynamic stability of the flow through an annulus composed of two concentric porous circular cylinders with the outer cylinder moving is examined. Axisymmetric disturbances of the flow, which is produced by a longitudinal pressure gradient, a cross-flow and boundary motion, are examined using numerical methods producing neutral stability curves which show that the flow is stabilized by boundary motion even in the presence of a destabilizing crossflow. Two special cases, annular Couette flow and transverse flow through an annulus, are also investigated and are found to be stable for small disturbances.

scholarly journals Cross Flow Through Closely-Arranged, Stagaered-Array Tube Banks.

1998 ◽  
Vol 64 (627) ◽  
pp. 3590-3596
Author(s):  
Hiroaki OHTOU ◽  
Kyozo AYUKAWA ◽  
Junji OCHI ◽  
Genta KAWAHARA ◽  
Motosuke SOGO
Keyword(s):  
Cross Flow ◽  
Flow Through ◽  
Tube Banks

Numerical Prediction of Fluid-Elastic Instability in Normal Triangular Tube Bundles With Multiple Flexible Circular Cylinders

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Hamed Houri Jafari ◽  
Behzad Ghadiri Dehkordi
Keyword(s):  
Tube Bundle ◽  
Equations Of Motion ◽  
Cross Flow ◽  
Structural Equations ◽  
Circular Cylinders ◽  
Staggered Grid ◽  
Elastic Instability ◽  
Time Step ◽  
Tube Bundles ◽  
Flow Through

Prediction of fluid-elastic instability onset is a great matter of importance in designing cross-flow heat exchangers from the perspective of vibration. In the present paper, the threshold of fluid-elastic instability has been numerically predicted by the simulation of incompressible, unsteady, and turbulent cross flow through a tube bundle in a normal triangular arrangement. In the tube bundle under study, there were single or multiple flexible cylinders surrounded by rigid tubes. A finite volume solver based on a Cartesian-staggered grid was implemented. In addition, the ghost-cell method in conjunction with the great-source-term technique was employed in order to directly enforce the no-slip condition on the cylinders' boundaries. Interactions between the fluid and the structures were considered in a fully coupled manner by means of intermittence solution of the flow field and structural equations of motion in each time step of the numerical modeling algorithm. The accuracy of the solver was validated by simulation of the flow over both a rigid and a flexible circular cylinder. The results were in good agreement with the experiments reported in the literatures. Eventually, the flow through seven different flexible tube bundles was simulated. The fluid-elastic instability was predicted and analyzed by presenting the structural responses, trajectory of flexible cylinders, and critical reduced velocities.

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