Steady lift-force generation on a circular cylinder utilising a longitudinal vortex: Influence of geometrical parameters

2021 ◽  
Vol 212 ◽  
pp. 104612
Author(s):  
Withun Hemsuwan ◽  
Kasumi Sakamoto ◽  
Tsutomu Takahashi
Keyword(s):  
Circular Cylinder ◽  
Lift Force ◽  
Longitudinal Vortex ◽  
Force Generation ◽  
Geometrical Parameters

scholarly journals Drag force of circular cylinder blade wind turbines driven by steady lift force of longitudinal vortex

2021 ◽  
Vol 87 (894) ◽  
pp. 20-00375-20-00375
Author(s):  
Kasumi SAKAMOTO ◽  
Withun HEMSUWAN ◽  
Tsutomu TAKAHASHI
Keyword(s):  
Circular Cylinder ◽  
Drag Force ◽  
Wind Turbines ◽  
Lift Force ◽  
Longitudinal Vortex

A novel wind / water turbine with circular cylinder blades driven by steady lift force caused by longitudinal vortex

2016 ◽  
Vol 2016 (0) ◽  
pp. 0617
Author(s):  
Tsutomu TAKAHASHI ◽  
Kasumi SAKAMOTO ◽  
Withun HEMSUWAN ◽  
Yumiko YOSHITAKE
Keyword(s):  
Circular Cylinder ◽  
Lift Force ◽  
Longitudinal Vortex ◽  
Water Turbine

The Numerical Simulation of Two-Degrees-of-Freedom Vortex-Induced Vibrations of Circular Cylinder with High Mass-Ratio

2013 ◽  
Vol 284-287 ◽  
pp. 557-561
Author(s):  
Jie Li Fan ◽  
Wei Ping Huang
Keyword(s):  
Circular Cylinder ◽  
Drag Force ◽  
Frequency Ratio ◽  
Lift Force ◽  
Degrees Of Freedom ◽  
Cross Flow ◽  
High Mass ◽  
Mass Ratio ◽  
Main Frequency ◽  
Line Amplitude

The two-degrees-of-freedom VIV of the circular cylinder with high mass-ratio is numerically simulated with the software ANSYS/CFX. The VIV characteristic is analyzed in the different conditions (Ur=3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion which is different from the cylinder with low mass-ratio can be obtained. When Ur is 3, the frequency of in-line VIV is twice of that of cross-flow VIV which is equal to the frequency ratio between drag force and lift force, and the in-line amplitude is much smaller than the cross-flow amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main frequency of in-line VIV is mainly the same as that of cross-flow VIV and the secondary frequency of in-line VIV is equal to the frequency of the drag force. The in-line amplitude is still very small compared with the cross-flow amplitude. When Ur is up to 8 and 10, the frequency of in-line VIV is the same as the main frequency of cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of drag force or lift force. But the secondary frequency of cross-flow VIV is equal to the frequency of the lift force. The amplitude ratio of the VIV between in-line and cross-flow direction is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval.

scholarly journals Numerical Investigation of Lift Force Increase in a Hovercraft by Changing the Geometrical Parameters of Flow Transfer Part and Air Channel

2020 ◽  
Vol 15 (30) ◽  
pp. 81-92
Author(s):  
Hossein Sadeghi ◽  
Mehrshad Yassari ◽  
Mohsen Pourfallah ◽  
Mohammad Molla Alipour ◽  
Ahmad Ali Rabienataj Darzi ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Lift Force ◽  
Geometrical Parameters ◽  
Force Increase ◽  
Air Channel ◽  
Flow Transfer

scholarly journals Experimental Studies on Fluctuating Lift Force on a Single Circular Cylinder at High Reynolds Numbers

1988 ◽  
Vol 1988 (37) ◽  
pp. 73-82
Author(s):  
K. FUJITA ◽  
Y. IKEGAMI ◽  
K. KOBAYASHI ◽  
M. OHASHI
Keyword(s):  
Circular Cylinder ◽  
Lift Force ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
High Reynolds Numbers ◽  
High Reynolds

scholarly journals Investigation of High Lift Force Generation of Dragonfly Wing by a Novel Advanced Mode in Hover

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Xiaohui Su ◽  
Kaixuan Zhang ◽  
Juan Zheng ◽  
Yong Zhao ◽  
Ruiqi Han ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Expenditure ◽  
Lift Force ◽  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
Dynamic Stall ◽  
Force Generation ◽  
High Lift ◽  
Dragonfly Wing ◽  
Symmetrical Mode

In the paper, a novel flapping mode is presented that can generate high lift force by a dragonfly wing in hover. The new mode, named partial advanced mode (PAM), starts pitching earlier than symmetric rotation during the downstroke cycle of the hovering motion. As a result, high lift force can be generated due to rapid pitching coupling with high flapping velocity in the stroke plane. Aerodynamic performance of the new mode is investigated thoroughly using numerical simulation. The results obtained show that the period-averaged lift coefficient, CL, increases up to 16% compared with that of the traditional symmetrical mode when an earlier pitching time is set to 8% of the flapping period. The reason for the high lift force generation mechanism is explained in detail using not only force investigation, but also by analyzing vortices produced around the wing. The proposed PAM is believed to lengthen the dynamic stall mechanism and enhance the LEV generated during the downstroke. The improvement of lift force could be considered as a result of a combination of the dynamic stall mechanism and rapid pitch mechanism. Finally, the energy expenditure of the new mode is also analyzed.

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