Experimental Investigation of Two Dimensional Motion of an Elastically Supported Cylinder in a Wake

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Robert D. Blevins ◽  
Jean-Francois Saint-Marcoux ◽  
Mason Wu
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Flow Velocity ◽  
Water Flow ◽  
Lift Force ◽  
Flow Channel ◽  
Two Dimensional ◽  
Elastically Supported ◽  
Made In

Measurements have been made of two dimensional motion of an elastically supported circular cylinder in the wake of a fixed upstream cylinder. The experiments were made in a water flow channel with 6.35cm(2.5in.) diameter cylinders with a maximum Reynolds number of 77,000. The elastically supported downstream cylinder moves downward and inward toward the centerline of the upstream cylinder’s wake with increasing flow velocity, indicating the presence of a transverse lift force and reduced drag in the wake. These forces can cause the cylinders to clash. The measured motions correlate with the theory.

Experimental Investigation of Vortex-Induced Vibration in One and Two Dimensions With Variable Mass, Damping, and Reynolds Number

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
Robert D. Blevins ◽  
Charles S. Coughran
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Vibration Amplitude ◽  
Variable Mass ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Vortex Induced Vibration ◽  
Frequency Entrainment ◽  
Elastically Supported

Measurements are made of vortex-induced vibration of an elastically supported circular cylinder in water with reduced velocity (U/fnD) from 2 to 12, damping factors (ζ) from 0.2% to 40% of critical damping, mass ratios (m/ρD2) from π/2 to π/17, and transverse, inline, and combined inline and transverse motions at Reynolds numbers up to 150,000. Effects of mass, damping, Reynolds number, and strakes on vortex-induced vibration amplitude, frequency, entrainment, and drag are reported.

The response of a turbulent boundary layer to lateral divergence

1979 ◽  
Vol 94 (2) ◽  
pp. 243-268 ◽  
Author(s):  
A. J. Smits ◽  
J. A. Eaton ◽  
P. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Turbulent Boundary Layer ◽  
Structural Parameters ◽  
Axial Flow ◽  
Turbulence Structure ◽  
Two Dimensional ◽  
Transition Section ◽  
Two Dimensional Flow ◽  
Made In

Measurements have been made in the flow over an axisymmetric cylinder-flare body, in which the boundary layer developed in axial flow over a circular cylinder before diverging over a conical flare. The lateral divergence, and the concave curvature in the transition section between the cylinder and the flare, both tend to destabilize the turbulence. Well downstream of the transition section, the changes in turbulence structure are still significant and can be attributed to lateral divergence alone. The results confirm that lateral divergence alters the structural parameters in much the same way as longitudinal curvature, and can be allowed for by similar empirical formulae. The interaction between curvature and divergence effects in the transition section leads to qualitative differences between the behaviour of the present flow, in which the turbulence intensity is increased everywhere, and the results of Smits, Young & Bradshaw (1979) for a two-dimensional flow with the same curvature but no divergence, in which an unexpected collapse of the turbulence occurred downstream of the curved region.

An Experimental Investigation of Flow Past a Smooth Circular Cylinder at the Sub-Critical Region

2002 ◽  
Author(s):  
Chuan He ◽  
Tianyu Long ◽  
Mingdao Xin ◽  
Benjamin T. F. Chung
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Critical Region ◽  
Algebraic Expression ◽  
Cylinder Surface ◽  
Local Pressure ◽  
Flow Past ◽  
Nadir Point ◽  
Experimental Findings

An experimental investigation for the incompressible flow past a smooth circular cylinder at the sub-critical region is presented in detail. A smooth circular cylinder is placed in a wind tunnel and the local pressure distribution on the cylinder surface is measured subtly. The Reynolds Number ranges from 104 to 8 × 104. The experimental data show that there exists a nadir point of the surface pressure in the front the across section of the cylinder and the pressure nadir position varies with the Reynolds number. It is found that this point tends to move forward of the cylinder as Reynolds number increases. Based on the present experimental findings, a simple algebraic expression describing the relationship between the location of the pressure’s nadir and Reynolds number is proposed.

Heat Transfer During Wind Flow over Rectangular Bodies in the Natural Environment

1981 ◽  
Vol 103 (2) ◽  
pp. 262-267 ◽  
Author(s):  
F. L. Test ◽  
R. C. Lessmann ◽  
A. Johary
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Wind Flow ◽  
Finite Width ◽  
Two Dimensional ◽  
Disturbance Intensity ◽  
Temperature Heat ◽  
Two Dimensional Flow ◽  
Transfer Behavior ◽  
Made In

An experimental investigation has been performed to determine the constant temperature heat transfer behavior on the upper surface of a rectangular plate with a chord length of 122 cm (48 in.), a width of 81.3 cm (32 in.) and a thickness aspect ratio of 6/1. Special side attachments were made in order to maintain approximately two-dimensional flow over the finite width body when exposed to varying wind directions. The angle of attack was 40 deg or greater. Quasi-local values of STRe were found to be 200 percent higher than wind tunnel values and 300 percent higher than analytical predictions. The disturbance intensity of the wind flow was in the range of 20 to 50 percent and is thought to be related to the increase in heat transfer since the flow over the plate was found to be laminar.

Computing internal viscous flow problems for the circle by integral methods

1977 ◽  
Vol 79 (3) ◽  
pp. 609-624 ◽  
Author(s):  
R. D. Mills
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Integral Representation ◽  
Analytical Solutions ◽  
Reynolds Numbers ◽  
Cylinder Wall ◽  
Two Dimensional ◽  
Discontinuous Surface ◽  
Flow Problems ◽  
Integral Methods

Steady two-dimensional viscous motion within a circular cylinder generated by (a) the rotation of part of the cylinder wall and (b) fluid entering and leaving through slots in the wall is considered. Studied in particular are moving-surface problems with continuous and discontinuous surface speeds, simple inflow–outflow problems and the impinging-jet problem within a circle. The analytical solutions at zero Reynolds number are given for the last two types of problem. Numerical results are obtained at various Reynolds numbers from the integral representation of the solution. At zero Reynolds number this approach involves a quadrature around the circumference of the cylinder. At other Reynolds numbers it involves an iterative–integral technique based on the use of the ‘clamped-plate’ biharmonic Green's function.

On a Circular Cylinder in a Uniform Planar Shear Flow at Subcritical Reynolds Number

2002 ◽  
Author(s):  
D. Sumner ◽  
O. O. Akosile
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Lift Force ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
Low Velocity ◽  
Static Pressure Distribution ◽  
Planar Shear ◽  
The Mean

An experimental investigation was conducted of a circular cylinder immersed in a uniform planar shear flow, where the approach velocity varies across the diameter of the cylinder. The study was motivated by some apparent discrepancies between numerical and experimental studies of the flow, and the general lack of experimental data, particularly in the subcritical Reynolds number regime. Of interest was the direction and origin of the steady mean lift force experienced by the cylinder, which has been the subject of contradictory results in the literature, and for which measurements have rarely been reported. The circular cylinder was tested at Reynolds numbers from Re = 4.0×104 − 9.0×104, and the dimensionless shear parameter ranged from K = 0.02 − 0.07, which corresponded to a flow with low to moderate shear. The results showed that low to moderate shear has no appreciable influence on the Strouhal number, but has the effect of lowering the mean drag coefficient. The circular cylinder develops a small steady mean lift force directed towards the low-velocity side, which is attributed to an asymmetric mean static pressure distribution on its surface. The reduction in the mean drag force, however, cannot be attributed solely to this asymmetry.

scholarly journals Experimental investigation of flow-induced vibration of a rotating circular cylinder

2017 ◽  
Vol 829 ◽  
pp. 486-511 ◽  
Author(s):  
K. W. L. Wong ◽  
J. Zhao ◽  
D. Lo Jacono ◽  
M. C. Thompson ◽  
J. Sheridan
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Rotation Rate ◽  
Rotating Cylinder ◽  
Flow Induced Vibration ◽  
Amplitude Response ◽  
Number Range ◽  
Rotating Circular Cylinder ◽  
Numerical Predictions

While flow-induced vibration of bluff bodies has been extensively studied over the last half-century, only limited attention has been given to flow-induced vibration of elastically mounted rotating cylinders. Since recent low-Reynolds-number numerical work suggests that rotation can enhance or suppress the natural oscillatory response, the former could find applications in energy harvesting and the latter in vibration control. The present experimental investigation characterises the dynamic response and wake structure of a rotating circular cylinder undergoing vortex-induced vibration at a low mass ratio ($m^{\ast }=5.78$) over the reduced velocity range leading to strong oscillations. The experiments were conducted in a free-surface water channel with the cylinder vertically mounted and attached to a motor that provided constant rotation. Springs and an air-bearing system allow the cylinder to undertake low-damped transverse oscillations. Under cylinder rotation, the normalised frequency response was found to be comparable to that of a freely vibrating non-rotating cylinder. At reduced velocities consistent with the upper branch of a non-rotating transversely oscillating cylinder, the maximum oscillation amplitude increased with non-dimensional rotation rate up to $\unicode[STIX]{x1D6FC}\approx 2$. Beyond this, there was a sharp decrease in amplitude. Notably, this critical value corresponds approximately to the rotation rate at which vortex shedding ceases for a non-oscillating rotating cylinder. Remarkably, at $\unicode[STIX]{x1D6FC}=2$ there was approximately an 80 % increase in the peak amplitude response compared to that of a non-rotating cylinder. The observed amplitude response measured over the Reynolds-number range of ($1100\lesssim Re\lesssim 6300$) is significantly different from numerical predictions and other experimental results recorded at significantly lower Reynolds numbers.

An experimental investigation of the oscillating lift and drag of a circular cylinder shedding turbulent vortices

1961 ◽  
Vol 11 (2) ◽  
pp. 244-256 ◽  
Author(s):  
J. H. Gerrard
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Cylinder Surface ◽  
Fluctuating Pressure ◽  
Order Of Magnitude ◽  
Lift And Drag

The oscillating lift and drag on circular cylinders are determined from measurements of the fluctuating pressure on the cylinder surface in the range of Reynolds number from 4 × 103 to just above 105.The magnitude of the r.m.s. lift coefficient has a maximum of about 0.8 at a Reynolds number of 7 × 104 and falls to about 0.01 at a Reynolds number of 4 × 103. The fluctuating component of the drag was determined for Reynolds numbers greater than 2 × 104 and was found to be an order of magnitude smaller than the lift.

Fouling Analysis on Energy Dissipation Orifice Plates With Sediment Contained Water Flow

2018 ◽  
Author(s):  
Jin-yuan Qian ◽  
Min-rui Chen ◽  
Zhi-xin Gao ◽  
Zhi-jiang Jin
Keyword(s):  
Reynolds Number ◽  
Energy Dissipation ◽  
Flow Velocity ◽  
Water Flow ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Orifice Plate ◽  
Sediment Particle ◽  
Perforated Plates ◽  
Sediment Volume

Hydropower stations play an important role in discharging the flood. Especially in wet seasons, the river water always contains several percentages of sediment, and the velocity of the water flowing through the flood discharging tunnel is very high. Arranging some energy dissipation orifice plates in the flood discharging tunnel, cannot only reduce the pressure and flow velocity, but also deposit sediment and reduce the sediment content. However, fouling on energy dissipation orifice plates can initiate material corrosion of perforated plates, even weaken the energy dissipation performance. In this paper, the fouling performance on energy dissipation orifice plates with sediment contained water flow is investigated. To begin with, the pressure along the path is used to compare with a reported experiment to verify the reliability of the numerical method. Then, effects of the solid particle diameter, the sediment volume concentration and the inlet flow velocity on the particle distribution are observed. The results show that with the increase of the Reynolds number, the sediment volume fraction and the sediment particle diameter, more sediments accumulate at both surfaces of the orifice plate. The Reynolds number and the sediment volume fraction affect the upstream surface more significantly, while the effect of sediment particle diameter is more notable on the downstream surface. Additionally, the energy dissipation coefficient of the orifice plate is mainly dominated by the Reynolds number. This work is of significance for further analysis of fouling problems in energy dissipation orifice plates or similar fluid machinery.

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