Study the effect of angle of attack on flow characteristics at racing bike helmet using CFD

At a cyclist drag racing champions greatly affect the speed of the bike, especially on the use of racing bike helmets. If the aerodynamic force from the racing bike helmet is getting smaller than the use of helmets on the bike racing will be more optimal and will affect the rate of the racer. In this study, numerical simulations were used to investigate the magnitude of the drag force that occurs around the surface of the helmet. With CFD software, 4 variations of attack angle 0°, 10°, 20° and 30° and variations of Reynold number 7.14x104, 1.00x105, and 1.16x105 are simulated to determine the flow characteristics of each state. The simulation results show that large area vortex is formed at the bottom of the helmet curve and dominates at the attack angle 30°. The result of the drag coefficient generated at the angle of attack 0° to 20° tends to decrease but at the attack angle 200 and 30° the drag coefficient increases