Abstract
The main role of conventional safety helmets is to protect the human head from external forces. So far the design of standardized helmets has placed an excessive emphasis on mechanical performance from this standpoint. During wearing the helmets, users experience high temperature rise in the head as well as excessive perspiration and an oppressive feeling. These discomforts prevent users from wearing the helmets. Behavior of air flow around the helmets needs to be studied in order to examine air cooling effects while users wear the helmets. Several techniques such as smoke wire, tuft and smoke injection methods have been applied to visualize air flows around the helmets which a mannequin wears in a low-velocity type wind tunnel. The pressure distributions on the outer surfaces of the helmets are measured on pressure transducers using diffusion type semiconductors. The stream lines and pressure distributions on the outer surfaces of the helmets are clarified by the present experiments. It is expected that the helmets are designed more rationally based on both fluid mechanics and the present experimental data.
