A comparison between physical and virtual experiments of convective heat transfer between head and bicycle helmet

Abstract

Thermal performance of five bicycle helmets was evaluated with a thermal manikin head with six zones. Evaluation was made with physical and virtual experimental methods. Ambient temperature maintained at 24 °C and surface temperature of the thermal manikin head was set to 34 °C. Experiments were performed for air velocities of 1.6 m/s and 6 m/s. Heat transfer (W) of four thermal zones was recorded for five helmets and compared with a nude thermal manikin head to assess thermal performance. Virtual experiments were performed using commercial CFD codes with a realizable k-e turbulence model. Correlation coefficients of 0.78 (1.6 m/s) and 0.79 (6 m/s) were found between physical and virtual experiments. A combined physical and virtual evaluation methodology allows creating a design iteration process with virtual prototypes, physical prototypes and commercially available helmets.