Aerodynamic drag measurements of FIFA-approved footballs
- Authors: Alam, Firoz , Chowdhury, Harun , George, Steven , Mustary, Israt , Zimmer, Gary
- Date: 2014
- Type: Text , Conference paper
- Relation: 2014 Conference of the International Sports Engineering Association p. 703-708
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- Description: Increasing technological advancements and demand for performance compel the ball manufacturers to introduce new designs. Construction of spherical footballs has been significantly changed over the years since 1970 from 32-panel leather stitched ball to 8-panel synthetic thermally bonded modern football. Despite being most popular game in the world, no data is available on aerodynamic properties of recently FIFA approved balls such as Adidas Cafusa (thermally bonded 32-panel), Nike Maxim (32- panel stitched), Umbro Neo (14-panel stitched, and Mitre Ultimax (26-panel stitched) footballs. Hence, the primary objective of this study was to determine aerodynamic drag of these balls and compare the findings with other balls introduced in late 2000. The aerodynamic forces were measured experimentally for a range of wind speeds in wind tunnel environment and their nondimensional coefficients were determined and compared. Additionally, a field test was also carried out to understand the perception of professional footballers.
Aerodynamics of ribbed bicycle racing helmets
- Authors: Alam, Firoz , Chowdhury, Harun , Wei, Hozhi , Mustary, Israt , Zimmer, Gary
- Date: 2014
- Type: Text , Conference paper
- Relation: 2014 Conference of the International Sports Engineering Association p. 691-696
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- Description: In competitive cycling, aero-helmets have been used around since 1980 to reduce aerodynamic resistance. Considerable design effort has been made to improve the aerodynamic efficiency of racing bicycle helmets over the years. However, the demand for further improvement has forced helmet manufacturers and designers to introduce new designs progressively. Recently several helmet manufacturers (e.g., LG, Lazer and Giro) have introduced dimples on the outer shell of helmet mimicking the so called 'Golf-ball' dimple effects with a view to further reduce aerodynamic drag of the helmet. However, no independently verifiable research so far has been reported in the public domain about the aerodynamic performance of ribbed bicycle helmets compared to smooth surfaced helmets. Hence, the primary objective of this work was to undertake an experimental study on four smooth aero-helmets including two latest model ribbed aero-helmets to understand their aerodynamic performance and the effect of dimples on helmets. The investigation was undertaken in an wind tunnel environment over a range of wind speeds, pitch and yaw angles. The experimental data indicate no measurable advantage between the smooth and ribbed helmets under varied pitch angles and at zero yaw angle.
On-road and wind tunnel aerodynamic study of human powered vehicles
- Authors: Alam, Firoz , Chowdhury, Harun , Guillaume, Erika , Yang, Jie , Zimmer, Gary
- Date: 2013
- Type: Text , Conference proceedings
- Full Text: false
- Description: The aim of the Royal Automotive Club of Victoria (RACV) Energy Breakthrough annual event is to provide an opportunity to school students to design and develop human powered vehicles (HPVs) and race a nonstop 24 hours event that requires energy conservation, endurance and reliability. The event involves primary and secondary school students, teachers, parents and local industry to work together on the design and use of energy efficient vehicles. The key areas with interest of HPVs are the significance of aerodynamic design and ways to improve overall aerodynamics as most HPVs are designed with minimal or no aerodynamic consideration. Therefore, the primary objective of this study is to examine the aerodynamic behaviour of two production HPVs of variable designs using on-road, wind tunnel experimentations and Computational Fluid Dynamics (CFD) modelling. The study shows that the aerodynamic efficiency of vehicle largely depends on external shape especially the extrusion, gaps and bumps. The useful data can be obtained and utilized using wind tunnel and on-road tests for HPVs if a close replica along is used. © 2013 The Authors.