Surface Roughness Effects on Vortex-Induced Vibration of Cylindrical Structures at Critical and Supercritical Reynolds Numbers

2001 ◽  
Author(s):  
D.W. Allen ◽  
D.L. Henning
Keyword(s):  
Surface Roughness ◽  
Reynolds Numbers ◽  
Roughness Effects ◽  
Vortex Induced Vibration ◽  
Cylindrical Structures

Surface Roughness Effects on Circular Cylinders at High Reynolds Numbers

2002 ◽  
Author(s):  
M. Eaddy ◽  
W. H. Melbourne ◽  
J. Sheridan
Keyword(s):  
Surface Roughness ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Flow Induced Vibration ◽  
Roughness Effects ◽  
Vortex Induced Vibration ◽  
Smooth Cylinder ◽  
Lift Forces ◽  
High Reynolds ◽  
Effect Of Surface

The problem of flow-induced vibration has been studied extensively. However, much of this research has focused on the smooth cylinder to gain an understanding of the mechanisms that cause vortex-induced vibration. In this paper results of an investigation of the effect of surface roughness on the cross-wind forces are presented. Measurements of the sectional RMS fluctuating lift forces and the axial correlation of the pressures for Reynolds numbers from 1 × 105 to 1.4 × 106 are given. It was found that surface roughness significantly increased the axial correlation of the pressures to similar values found at high subcritical Reynolds numbers. There was little effect of the surface roughness on the sectional lift forces. The improved correlation of the vortex shedding means rough cylinders will be subject to larger cross-wind forces and an increased possibility of vortex-induced vibration compared to smooth cylinders.

Measurements and Predictions of Surface Roughness Effects on the Turbine Vane Aerodynamics

2003 ◽  
Author(s):  
R. J. Boyle ◽  
R. G. Senyitko
Keyword(s):  
Surface Roughness ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Roughness Effects ◽  
Linear Cascade ◽  
Wide Range ◽  
Turbine Vane

The aerodynamic performance of a turbine vane was measured in a linear cascade. These measurements were conducted for exit-true chord Reynolds numbers between 150,000 and 1,800,000. The vane surface rms roughness-to-true chord ratio was approximately 2 × 10−4. Measurements were made for exit Mach numbers between 0.3 and 0.9 to achieve different loading distributions. Measurements were made at three different inlet turbulence levels. High and intermediate turbulence levels were generated using two different blown grids. The turbulence was low when no grid was present. The wide range of Reynolds numbers was chosen so that, at the lower Reynolds numbers the rough surfaces would be hydraulically smooth. The primary purpose of the tests was to provide data to verify CFD predictions of surface roughness effects on aerodynamic performance. Data comparisons are made using a two-dimensional Navier-Stokes analysis. Both two-equation and algebraic roughness turbulence models were used. A model is proposed to account for the increase in loss due to roughness as the Reynolds number increases.

Roughness Effects on Frictional Resistance of Enclosed Rotating Disks

1960 ◽  
Vol 82 (3) ◽  
pp. 553-560 ◽  
Author(s):  
R. E. Nece ◽  
J. W. Daily
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Initial Point ◽  
Frictional Resistance ◽  
Reynolds Numbers ◽  
Tip Clearance ◽  
Rotating Disks ◽  
Roughness Effects ◽  
Disk Radius ◽  
Onset Of Turbulence

The effects of surface roughness on the frictional resistance of enclosed rotating disks have been studied experimentally. Torque data were obtained over the range of disk Reynolds numbers 4 × 103 to 6 × 106 for three different relative roughnesses a/k of 1000, 2000, and 3200 at three axial-clearance-to-disk-radius ratios s/a of 0.0227, 0.0609, and 0.112 for a constant, small, radial tip clearance. The existence of four possible basic flow regimes in the axial gap between the disk and casing wall was verified. Empirical expressions have been presented which predict the initial point of onset of turbulence in the flow within the boundary layer on the disk, the point at which the surface roughness becomes fully effective, and the magnitudes of the resistance coefficients in the zone of fully rough turbulent flow. The similarities and differences between smooth and rough-disk torque behavior, and to a limited extent boundary-layer behavior, have been noted.

Velocity Distribution in Turbulent Flow

1970 ◽  
Vol 12 (6) ◽  
pp. 391-399 ◽  
Author(s):  
W. K. Allan
Keyword(s):  
Surface Roughness ◽  
Turbulent Flow ◽  
Velocity Distribution ◽  
Flat Plate ◽  
Reynolds Numbers ◽  
Pressure Gradients ◽  
Roughness Effects ◽  
High Reynolds ◽  
Independent Effects ◽  
Good Agreement

A general equation for the velocity distribution in steady, incompressible, two-dimensional, turbulent flow is constructed by correction of the logarithmic velocity profile for the independent effects of pressure gradients and of surface roughness. Predicted characteristics of pipe flows, flat plate flows, and diffusing flows over smooth surfaces are found to be in good agreement with empirical data at high Reynolds numbers. Pipe flow data are used to evaluate surface roughness effects, and hence to describe flat plate flows and diffusing flows over rough surfaces.

Vortex Induced Vibration Tests of Smooth and Rough Flexible Cylinders at High Reynolds Numbers

2005 ◽  
Author(s):  
Don W. Allen ◽  
Dean L. Henning ◽  
Li Lee
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Single Mode ◽  
Reynolds Numbers ◽  
Circular Path ◽  
Exterior Surface ◽  
Vortex Induced Vibration ◽  
High Reynolds Numbers ◽  
Sheared Flows ◽  
High Reynolds

Vortex-induced vibration (VIV) tests have been performed on long, flexible pipes with various levels of roughness, in sheared flows in a circular towing tank at high Reynolds numbers. The test pipes, made of fiberglass composite, were mounted horizontally beneath a rotating arm that has a span of 129 ft, and a width of 25 ft. As the towing bridge rotates, it drives the cylinder in a circular path in still water. The sheared flows experienced by the cylinder excite its VIV motion. The Reynolds numbers for the tests reported herein ranged from 152,000 to 339,000 at the high-speed end of the pipe. Two surface roughness levels were tested: one comprised of the exterior surface of a filament wound fiberglass pipe; and one with carpet glued to the exterior of the pipe. The VIV responses of the test cylinders, represented by displacement time traces, spectrum, and motion trajectories, are presented in this paper. Effects of the surface roughness and Reynolds numbers on the VIV responses are discussed. The response behavior of the cylinders varied from single-mode dominance to multi-mode responses, in addition to certain traveling wave activities. These results should be of interest to researchers and engineers in the area of vortex-induced vibrations.

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade— Part II: Aerodynamic Losses

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Roughness Effects ◽  
Aerodynamic Losses

The present experimental study is part of a comprehensive analysis accounting for heat transfer and aerodynamic losses on a highly loaded low pressure turbine blade with varying surface roughness. Whereas Part I focuses on heat transfer measurements at airfoil midspan with different deterministic surface roughnesses, Part II investigates surface roughness effects on aerodynamic losses of the same airfoil. A set of different arrays of deterministic roughness (the same as used in Part I) is investigated in these experiments. The height and eccentricity of the roughness elements are varied, showing the combined influence of roughness height and anisotropy on the losses produced in the boundary layers. It is shown that the boundary layer loss is dominated by the suction side. Therefore, the investigations focus on measurements of the suction side boundary layer thickness at midspan directly upstream of the trailing edge. The experiments are conducted at several freestream turbulence levels (Tu1=1.4–10.1%) and different Reynolds numbers. The measurements reveal that suction side boundary layer thickness is increased by up to 190% if surface roughness shifts the transition onset upstream. However, in some cases, at low Reynolds numbers and freestream turbulence, surface roughness suppresses boundary layer separation and decreases the trailing edge boundary layer thickness by up to 30%.

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade: Part II—Aerodynamic Losses

2010 ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Free Stream ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Roughness Effects ◽  
Free Stream Turbulence ◽  
Aerodynamic Losses

The present experimental study is part of a comprehensive analysis accounting for heat transfer and aerodynamic losses on a highly loaded low pressure turbine blade with varying surface roughness. Whereas part I focuses on heat transfer measurements at airfoil midspan with different deterministic surface roughnesses, part II investigates surface roughness effects on aerodynamic losses of the same airfoil. A set of different arrays of deterministic roughness (the same as used in part I) is investigated in these experiments. The height and eccentricity of the roughness elements is varied, showing the combined influence of roughness height and anisotropy on the losses produced in the boundary layers. It is shown that the boundary layer loss is dominated by the suction side. Therefore, the investigations focus on measurements of the suction side boundary layer thickness at midspan directly upstream of the trailing edge. The experiments are conducted at several free-stream turbulence levels (Tu1 = 1.4% to 10.1%) and different Reynolds numbers. The measurements reveal that suction side boundary layer thickness is increased by up to 190% if surface roughness shifts the transition onset upstream. However, in some cases, at low Reynolds numbers and free-stream turbulence, surface roughness suppresses boundary layer separation and decreases the trailing edge boundary layer thickness by up to 30%.

scholarly journals Surface roughness effects on a tensioned riser vortex-induced vibration in the uniform current

2021 ◽  
pp. 102970
Author(s):  
Xiangxi Han ◽  
Youhong Tang ◽  
Zhanbin Meng ◽  
Weidong Ruan ◽  
Ang Qiu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Roughness Effects ◽  
Vortex Induced Vibration ◽  
Uniform Current
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