The computational simulation of flow around the helmet cycling used in time trial stages is of great importance because it allows understanding the phenomena occurring and thereby obtain detailed information of flow field and causes of aerodynamic drag. The aim of such studies is to improve sports performance athlete/cyclist through positions on the bike or helmet with less aerodynamic drag. The simulation of the helmet was based on the time trial position and varied the position of the helmet relative to the cervical area for three different positions: 0º, 30º and 60º. For this purpose various forms of helmets have been created in order to understand the influence of shape on the coefficient of drag and it was defined the computational domain and boundary conditions for the case study. The results in ANSYS FLUENT show that the shape, the inclination and the frontal area of the helmet has a large influence on the aerodynamics. By increasing the inclination, the projected frontal area would lead to greater air resistance. The main source of drag was due to the form drag that causes a difference in pressure between the front and back of the helmet. The contribution due to viscous friction at the surface is no relevance. The smaller helmets had a better performance for the third position (60º), but in the other positions it was found that didn`t favor the aerodynamics, since it was obtained for higher values of drag. In turn the helmets with a bigger tail, showed lower values of coefficient of drag for position 1 (0º). The helmet most aerodynamic was optimized using three different models and obtained a lower drag coefficient, due to the reduced frontal area and the shape used, and a model obtained lower drag resistance. Through a quantitative analysis of reducing aerodynamic drag and the energy saved, the use of an aerodynamic helmet allows a reduction of air resistance and thus the rider saves some power. This analysis was to compare the aerodynamic helmets for a normal helmet with and without vents. The time saved for a cyclist was also calculated in which the ideal position was held (and presents a more aerodynamic helmet) in relation to another rider that varies the position (and presents a less aerodynamic helmet), the parameter of coefficient of drag varied and it was found that some time can be saved (in this study was about 116 seconds). The vents incorporated in front of the helmet did not significantly affect the value of coefficient of drag. The same didn`t happen for the normal helmet because
© Copyright 2010 Alle Rechte vorbehalten.