This　study　aims　to　figure　out　some　safety　issues　by　investigating　the　roof　shape　of　infrastructures　such　as　zero-carbon　huts　that　people　are　already　using　to　prevent　dangerous　hydrogen　clouds　from　building　up　in　places　with　little　airflow　when　there　is　a　leak.　We　designed　three　different　obstacles.　The　horizontal　and　vertical　concentration　distributions　of　the　free-jet　hydrogen　cloud　when　encountering　different　obstacles　were　determined　by　concentration　measurements.　In　addition,　the　diffusion　characteristics　of　the　hydrogen　jet　in　the　presence　of　obstacles　were　investigated　by　using　the　Background　Oriented　Schlieren　(BOS).　The　results　show　that　there　is　a　linear　relationship　between　the　measured　axial　concentration　of　the　hydrogen　jet　and　the　leakage　parameters　at　lower　flow　rates.　The　measured　radial　concentration　of　the　hydrogen　jet　shows　a　“Gaussian-like”　distribution　when　encountering　a　flat　plate　obstacle,　a　“W”　distribution　when　encountering　a　flat　plate　obstacle　with　sidewalls,　and　a　“W-like”　distribution　when　encountering　a　dome-type　obstacle.　A　method　of　inverting　the　radial　concentration　distribution　of　the　hydrogen　jet　using　the　BOS　is　also　proposed,　and　the　error　between　the　theoretical　and　experimental　values　is　calculated　to　be　3.81　%.　This　study　stresses　the　significance　of　geometric　and　dimensional　parameters　on　hydrogen　leakage　characteristics　and,　as　a　result,　provides　insights　into　developing　performance　standards　for　the　availability　and　reliability　of　safety-critical　systems.　©　2024