scholarly journals Vortex-Induced Vibration Suppression of a Circular Cylinder with Vortex Generators

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Shi-bo Tao ◽  
Ai-ping Tang ◽  
Da-bo Xin ◽  
Ke-tong Liu ◽  
Hong-fu Zhang
Keyword(s):  
Circular Cylinder ◽  
Vibration Suppression ◽  
Angular Position ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Spanwise Direction ◽  
Control Effect ◽  
Vortex Induced Vibration ◽  
Suppression Method ◽  
Skew Angles

The vortex-induced vibration is one of the most important factors to make the engineering failure in wind engineering. This paper focuses on the suppression method of vortex-induced vibration that occurs on a circular cylinder fitted with vortex generators, based on the wind tunnel experiment. The effect of the vortex generators is presented with comparisons including the bare cylinder. The experimental results reveal that the vortex generators can efficiently suppress vortex-induced vibration of the circular cylinder. Vortex generator control can make the boundary layer profile fuller and hence more resistant to separation. The selections of skew angles and the angular position have a significant influence on the vortex generator control effect. By correlation analysis, it can be concluded that the vortex generators can inhibit the communication between the two shear layers and produce streamwise vortices to generate a disturbance in the spanwise direction.

The Influence of Vortex Generators on the Drag and Heat Transfer From a Circular Cylinder Normal to an Airstream

1969 ◽  
Vol 91 (1) ◽  
pp. 91-99 ◽  
Author(s):  
T. R. Johnson ◽  
P. N. Joubert
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Angular Position ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Experimental Investigations ◽  
Stagnation Line

Experimental investigations were carried out to examine the effect of vortex generators on drag and heat transfer from a circular cylinder in a crossflow. The cylinder was fitted with two rows of vortex generators which were symmetrically placed on either side of and parallel to the front stagnation line. One configuration of vortex generator was used and the angular position of the rows from the front stagnation line was varied. In the heat transfer runs the vortex generator position remained unvaried. Results are presented to show the variation of drag coefficient with Reynolds number for several angular positions of the generator rows. Results are also presented to show the variation of Nusselt number with Reynolds number both for a cylinder with and without generators. These show that both decreases in drag coefficient and increases in Nusselt number can be obtained when vortex generators are fitted.

scholarly journals Numerical Investigation on Vortex-Induced Vibration Suppression of a Circular Cylinder with Axial-Slats

2019 ◽  
Vol 7 (12) ◽  
pp. 454 ◽  
Author(s):  
Wei Wang ◽  
Zhaoyong Mao ◽  
Wenlong Tian ◽  
Tingying Zhang
Keyword(s):  
Circular Cylinder ◽  
Frequency Ratio ◽  
Vibration Suppression ◽  
Amplitude Ratio ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Suppression Effect ◽  
Coverage Ratio ◽  
Region I ◽  
Region Ii

The vortex-induced vibration (VIV) suppression of a circular cylinder with the axial-slats is numerically investigated using the computational fluid dynamics (CFD) method for Reynolds number range of 8.0 × 103–5.6 × 104. The two-dimensional unsteady Reynolds averaged Navier–Stokes (RANS) equations and Shear-Stress-Transport (SST) turbulence model are used to calculate the flow around the cylinder in ANSYS Fluent. The Newmark-β method is used to evaluate structural dynamics. The amplitude response, frequency response and vortex pattern are discussed. The suppression effect of the axial-slats is the best when the gap ratio is 0.10 and the coverage ratio is 30%. Based on the VIV response, the whole VIV response region is divided into four regions (Region I, Region II, Region III and Region IV). The frequency ratio of isolated cylinder jumps between region II and region III. However, the frequency ratio jumps between region I and region II for a cylinder with the axial-slats. The axial-slats destroy the original vortex and make the vortex easier to separate. The online amplitude ratio is almost completely suppressed, and the cross-flow amplitude ratio is significantly suppressed.

Vibration suppression method of humanoid flexible arm based on model-free predictive control

2021 ◽  
pp. 1-9
Author(s):  
Qinjun Du ◽  
Chuanming Song ◽  
Wei Ding ◽  
Long Zhao ◽  
Yonggang Luo
Keyword(s):  
Predictive Control ◽  
Vibration Suppression ◽  
Model Free ◽  
Flexible Arm ◽  
Suppression Method

Steady longitudinal vortices in supersonic turbulent separated flows

2011 ◽  
Vol 672 ◽  
pp. 451-476 ◽  
Author(s):  
ERICH SCHÜLEIN ◽  
VICTOR M. TROFIMOV
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Roughness Element ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Leading Edge ◽  
Separated Flows ◽  
Vortex Generators ◽  
Longitudinal Vortices ◽  
Oil Flow

Large-scale longitudinal vortices in high-speed turbulent separated flows caused by relatively small irregularities at the model leading edges or at the model surfaces are investigated in this paper. Oil-flow visualization and infrared thermography techniques were applied in the wind tunnel tests at Mach numbers 3 and 5 to investigate the nominally 2-D ramp flow at deflection angles of 20°, 25° and 30°. The surface contour anomalies have been artificially simulated by very thin strips (vortex generators) of different shapes and thicknesses attached to the model surface. It is shown that the introduced streamwise vortical disturbances survive over very large downstream distances of the order of 104 vortex-generator heights in turbulent supersonic flows without pressure gradients. It is demonstrated that each vortex pair induced in the reattachment region of the ramp is definitely a child of a vortex pair, which was generated originally, for instance, by the small roughness element near the leading edge. The dependence of the spacing and intensity of the observed longitudinal vortices on the introduced disturbances (thickness and spanwise size of vortex generators) and on the flow parameters (Reynolds numbers, boundary-layer thickness, compression corner angles, etc.) has been shown experimentally.

scholarly journals On the formation of streamwise vortices by plasma vortex generators

2013 ◽  
Vol 733 ◽  
pp. 370-393 ◽  
Author(s):  
Timothy N. Jukes ◽  
Kwing-So Choi
Keyword(s):  
Boundary Layer ◽  
Flow Direction ◽  
Vortex Formation ◽  
Vortex Generator ◽  
Streamwise Vortex ◽  
Spanwise Direction ◽  
Formation Mechanisms ◽  
Wall Jet ◽  
Streamwise Vortices ◽  
Barrier Discharge Plasma

AbstractThe streamwise vortices generated by dielectric-barrier-discharge plasma actuators in the laminar boundary layer were investigated using particle image velocimetry to understand the vortex-formation mechanisms. The plasma vortex generator was oriented along the primary flow direction to produce a body force in the spanwise direction. This created a spanwise-directed wall jet which interacted with the oncoming boundary layer to form a coherent streamwise vortex. It was found that the streamwise vortices were formed by the twisting and folding of the spanwise vorticity in the oncoming boundary layer into the outer shear layer of the spanwise wall jet, which added its own vorticity to increase the circulation along the actuator length. This is similar to the delta-shaped, vane-type vortex generator, except that the circulation was enhanced by the addition of the vorticity in the plasma jet. It was also observed that the plasma vortex was formed close to the wall with an enhanced wall-ward entrainment, which created strong downwash above the actuator.

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