Abstract
Fuel-cell vehicles are designed so that hydrogen leaks from the tank are stopped automatically upon detection of hydrogen leakage or detection of impact in a collision. However, to understand a possible scenario if the automatic system fails, we investigated the characteristics of hydrogen leakage sound from a hydrogen-leaking vehicle and characteristics of an alternative gas that is equal to the noise level of a hydrogen leak sound. We conducted hearing tests in an anechoic chamber to clarify how to rescue people safely in the event of a continuous hydrogen leak, depending on the sense of human hearing. As a result, we found that because of the audible characteristics of hydrogen leaks from vehicles, when approaching a hydrogen-leaking vehicle, it is best to first listen while walking around the vehicle and then approach from the maximum sound direction. In addition, a leak becomes difficult to hear when subjects are very close the vehicle. We also found that there is a linear relationship between hydrogen and helium flow rates when converting them using the noise levels in front of the vehicle. The sound pressure level of the hydrogen leaking from a pipe installed in the lower part of the vehicle and that of a helium leak are almost equal.
