0
Flows in Complex Systems

Aerodynamics of Fixed and Rotating Spoked Cycling Wheels

[+] Author and Article Information
S. J. Karabelas

N. C. Markatos

Department of Chemical Engineering - Computational Fluid Dynamics Unit,  National Technical University of Athens (N.T.U.A.), 157 80 Athens, Greece

J. Fluids Eng 134(1), 011102 (Feb 09, 2012) (14 pages) doi:10.1115/1.4005691 History: Received January 07, 2011; Revised December 20, 2011; Published February 08, 2012; Online February 09, 2012

The performance of a semiracing spoked wheel is numerically and experimentally studied at full size in a wind tunnel. The numerical investigation is divided into two parts. In the first part, the wheel is considered to be fixed (no rotation) and the numerical results are compared to the experimental measurements. The flow past the wheel is treated as stationary and turbulent. The effects of cross wind and the wheel’s speed on the drag, side force, and yaw moment are investigated. Numerical results are presented via diagrams and plots at various yaw angles. Both the measurements and predictions agree quite well and they show a considerable increase in the yaw moment and side force at medium and high yaw angles. The axial drag force initially increases with yaw angle (up to 7.5 deg) and eventually decreases. Ground effects did not affect the overall loads, except for the vertical force at high yaw angles. In the second part, the effects of rotation have been taken into account. The wheel rotates at constant angular velocities and the flow is modeled as nonstationary and turbulent. The aerodynamic performance of the wheel is strongly affected by the rotational speed. In most of the cases, as the latter parameter increases, the loads nonlinearly increase. The rotation generates asymmetrical loading, since the flow is accelerated in one side and decelerated in the other (the Magnus effect). A vertical force is produced, which is dependent on the ratio of the rotational to the free-stream speed. Moreover, in an attempt to assess the effects of the number of spokes to the aerodynamic performance, two other models with 8 and 32 spokes have been numerically tested and compared to the original one (16 spokes). The results revealed, as expected, an increase in the axial drag and vertical force with the number of spokes.

Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Real and CAD model used for the simulations

Grahic Jump Location
Figure 2

Force resolution and reference parameters

Grahic Jump Location
Figure 3

Computational domain and the imposed boundary conditions

Grahic Jump Location
Figure 4

Skin friction distribution along the wheel’s perimeter

Grahic Jump Location
Figure 5

The 16-spoked wheel WHR540 in the wind tunnel. The glass plates simulate the ground effects.

Grahic Jump Location
Figure 6

Frontal view of the area of the experiment

Grahic Jump Location
Figure 7

Static pressure contours on the wheel’s surface at cycling velocity V = 10 m/s

Grahic Jump Location
Figure 8

Axial drag coefficient variation with yaw angle

Grahic Jump Location
Figure 9

Side force coefficient variation with yaw angle

Grahic Jump Location
Figure 10

Vertical force coefficient plotted against the yaw angle

Grahic Jump Location
Figure 11

Yaw moment coefficient versus yaw angle

Grahic Jump Location
Figure 12

Yaw moment coefficient versus side force coefficient

Grahic Jump Location
Figure 13

Axial force of every wheel component plotted against yaw angle at V = 10 m/s

Grahic Jump Location
Figure 14

Side force of every wheel component plotted against yaw angle at V = 10 m/s

Grahic Jump Location
Figure 15

Axial force time variation for three wheels of 8, 16 and 32 spokes

Grahic Jump Location
Figure 16

Side force time variation for three wheels of 8, 16 and 32 spokes

Grahic Jump Location
Figure 17

Axial drag coefficient versus rotation angle at ω = 10 rad/s, ω = 30 rad/s and ω = 50 rad/s and at a = 0 deg, a = 15 deg, and a = 30 deg. The free-stream speed is fixed at V = 10 m/s.

Grahic Jump Location
Figure 18

Side force coefficient at a = 10 deg versus rotation angle for various types of wheels. The free-stream speed for the present wheel WHR540 is V = 10 m/s, while for the other three designs is 8.88 m/s [7].

Grahic Jump Location
Figure 19

Side force coefficient versus rotation angle at ω = 10 rad/s, ω = 30 rad/s and ω = 50 rad/s and at a = 15 deg and a = 30 deg. The free-stream speed is fixed at V = 10 m/s.

Grahic Jump Location
Figure 20

Yaw moment coefficient versus rotation angle at ω = 10 rad/s, ω = 30 rad/s and ω = 50 rad/s and at a = 0 deg, a = 15 deg and a = 30 deg. The free-stream speed is fixed at V = 10 m/s.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In