CFD comparison of friction and pressure drag road and time trial helmets for wheelchair racing

• Main Author: Forte, Pedro
• Publication Date: 2017
• Other Authors: Marinho, D.A., Morais, J.E., Morouço, Pedro, Barbosa, Tiago M.
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10198/14296
• topic: Friction; Pressure

Computer Fluid Dynamics has been used by sports scientists aiming to improve the athlete’s performance in sprinting events. In wheelchair sprinting, the athlete’s velocity can reach up to 7m/s. The use of sport garments such as helmets may reduce the aerodynamic drag by 10%. Therefore, the aim of this study was to compare the friction and pressure drag between road and time trial helmets. A wheelchair racer (category T-52), European medallist in sprinting events and world championships finalist was recruited for this research. The subject wore a road helmet (LAS, Istron) and a time-trial model (LAS, Cronometro). The geometries were obtained by a 3D scan (Artec-L, Artec Group, Inc., USA). Fluent (Fluent, Inc., USA, New York) code allowed to compute numerical simulations applying a mathematical model to the fluid flow, in a created domain with discretized expressions of the Navier-Stokes equations. It solves the equations with a finite volume approach. The domain, created by a 3D mesh of subdivided cells, represented the fluid flow around the head and helmets. Realizable k-epsilon turbulence model was applied. The 3D mesh had more than 6 million cells for booth helmets domains and helmets angles of attack was 0º. The fluid flow velocity was set in inlet portion of the dome surface at 2m/s, with increments of 1.5 m/s up to 6.5 m/s. Typically the wheelchair racer will reach these range of speeds over a short distance event. Pressure and friction drag increased with velocity