Study on the variation law of explosion strength parameters in the hybrid explosion of hydrogen and titanium dust

The hydrogen/titanium powder two-phase system readily forms during the application of titanium-based solid-state hydrogen storage technology and the production and processing of titanium metal products, posing a high explosion risk. To investigate the explosion characteristics of this hydrogen/titanium powder two-phase system, this study employed a 20 L spherical explosion apparatus. Within a range of hydrogen concentrations from 0% to 30% and titanium powder concentrations from 100 to 700 g/m³, the variation patterns of explosion intensity parameters were examined. Combined with analysis of the explosion products, the formation mechanisms underlying these parameter variations were elucidated.The results indicate that the presence of hydrogen significantly affects the explosion intensity of titanium powder.Overall, within the titanium powder concentration range of 100-700 g/m³, the explosion pressure<italic>P</italic>_ex first decreases, then increases, and finally decreases again as hydrogen concentration rises. It reaches its minimum at a hydrogen concentration of 4% and its maximum at 29%. The rate of increase in explosion pressure (d<italic>P</italic>/d<italic>t</italic>)_ex first decreases then increases with rising hydrogen concentration. It reaches its minimum at 4% hydrogen concentration and its maximum at 30% hydrogen concentration.The maximum explosion pressure <italic>P</italic>_max of the hydrogen/titanium powder two-phase system also decreases initially, then increases, and finally decreases again with increasing hydrogen concentration. It reaches its lowest point at a hydrogen concentration of 4% and peaks at 29%. The maximum explosion pressure rise rate (d<italic>P</italic>/d<italic>t</italic>)_max first decreases then increases with increasing hydrogen concentration. It reaches its minimum at 4% hydrogen concentration and subsequently rises continuously, peaking at 30% hydrogen concentration.Analysis of explosion products indicates that low hydrogen concentrations cause or exacerbate incomplete oxidation reactions in titanium powder, thereby reducing both the explosion pressure <italic>P</italic>_ex and the explosion pressure rise rate (d<italic>P</italic>/d<italic>t</italic>)_ex.When the hydrogen concentration increases to the critical value, the spontaneous combustion of hydrogen promotes the reaction between titanium powder and nitrogen, causing the two-phase system's explosion process to transition from heterogeneous combustion to homogeneous combustion. This transition leads to an increase in both the explosion pressure <italic>P</italic>_ex of the titanium powder and the rate of pressure rise (d<italic>P</italic>/d<italic>t</italic>)_ex.