Effects of solar environment and aerodynamic drag on structural booms in space

1966 ◽  
Author(s):  
S. FIXLER
Keyword(s):  
Aerodynamic Drag

A Study of an Active Rear Diffuser Device for Aerodynamic Drag Reduction of Automobiles

2012 ◽  
Author(s):  
Seung-On Kang ◽  
Jun-Ho Cho ◽  
Sang-Ook Jun ◽  
Hoon-Il Park ◽  
Ki-Sun Song ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Aerodynamic Drag ◽  
Aerodynamic Drag Reduction

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

Enabling Dynamic Behaviors With Aerodynamic Drag in Lightweight Tails

2021 ◽  
pp. 1-10
Author(s):  
Joseph Norby ◽  
Jun Yang Li ◽  
Cameron Selby ◽  
Amir Patel ◽  
Aaron M. Johnson
Keyword(s):  
Aerodynamic Drag ◽  
Dynamic Behaviors

scholarly journals The dependence of the brake disc aerodynamic drag on the rolling stock motion speed

2021 ◽  
Vol 55 ◽  
pp. 723-730
Author(s):  
Juraj Gerlici ◽  
Yuliia Fomina ◽  
Kateryna Kravchenko
Keyword(s):  
Aerodynamic Drag ◽  
Rolling Stock ◽  
Brake Disc ◽  
Motion Speed

Nonlinear dynamic behaviour of guy cables in turbulent winds

2001 ◽  
Vol 28 (1) ◽  
pp. 98-110 ◽  
Author(s):  
Bruce F Sparling ◽  
Alan G Davenport
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Horizontal Displacement ◽  
Wind Loading ◽  
Second Phase ◽  
Nonlinear Coupling ◽  
Wide Range ◽  
Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

scholarly journals Factors affecting the aerodynamic drag of alpine skiers

2010 ◽  
Vol 2 (2) ◽  
pp. 2375-2380 ◽  
Author(s):  
Len Brownlie ◽  
Guy Larose ◽  
Annick D’Auteuil ◽  
Todd Allinger ◽  
Frank Meinert ◽  
...  
Keyword(s):  
Aerodynamic Drag ◽  
Factors Affecting ◽  
Alpine Skiers

On the correlation between aerodynamic drag and wake flow for a generic high-speed train

2021 ◽  
Vol 215 ◽  
pp. 104698
Author(s):  
Xiao-Bai Li ◽  
Xi-Feng Liang ◽  
Zhe Wang ◽  
Xiao-Hui Xiong ◽  
Guang Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Aerodynamic Drag ◽  
Wake Flow ◽  
High Speed Train
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