Abstract
When high pressure hydrogen jet is emitted atmosphere, the hydrogen jet may be ignited automatically. On this problem, shock wave produced by breaking diaphragm may influence the phenomena. To clarify the influence of shock wave, two types of experiment are carried out. The first one is in the condition where the extend tube is not equipped to examine the expansion effect of shock wave. The second is in the condition where the extend tube is provided due to the enhancement of shock wave after breaking diaphragm. As a result, auto ignition was obtained in the second condition. It was found that parameters of the hydrogen pressure and the extend tube were significant for the phenomenon.
