## 5 Conclusions  
In this paper, the coupled effects of obstacle angle and position on the deflagration characteristics of H\({}_{2}\)/CH\({}_{4}\) premix were analyzed through experiments and LES simulations. The main conclusions are as follows:  
1. When the obstacle was placed at 200 mm, the flame was stretched axially through the obstacle in the shape of a \"jellyfish\" up to the mouth of the pipe. As the angle of the obstacle increased, the length of the obstacle decreased and the tail branch of the flame became shorter and shorter. When the obstacle was placed at 500 mm and 800 mm, the flame broke up after passing through the obstacle, and the breakup effect became more intense with the increase in the angle. A tulip-like flame shape appeared behind the Case 2/5/8/11 obstacles.
2. Obstacles to the flame caused by the shear effect are a key factor in the substantial change in the flame area. When the obstacle was located in the middle position, it had a significant effect on the maximum value of the flame front fold and area, followed by 200 mm, and finally 800 mm. In addition, as the obstacle was closer to the vent, the flame area gradually reduced under the influence of the obstacle angle.
3. Obstacles near the deflagration port were able to reduce the maximum blast pressure, and Case 3 had the smallest pressure for the four angular conditions. In addition, the minimum explosion overpressure occurred at different angles for the three obstacle positions. For Case 2/5/8/11, gas expansion created vortices and further enhanced the turbulence intensity, leading to more intense mixing in the flow field and the maximum peak explosion pressure. In addition, the closer the obstacle was to the ignition source, the faster the flame reached the vent, and the earlier the pressure peak appeared.  
The findings of this study help to understand the effect of obstacles on explosion characteristics. This can be used to more accurately assess explosion risk in specific environments and formulate appropriate safety standards and contingency plans to ensure the safety of property and people. In future work, further in-depth study of the effect of different obstacles on the explosion characteristics of hydrogen-doped natural gas is necessary, as well as further research on flame propagation and explosion characteristics at different hydrogen concentrations.  
Conceptualization, Y.H. and J.G.; methodology, Y.H.; validation, Y.H.; formal analysis, Y.H., Y.W., and X.S.; writing--original draft preparation, Y.H.; writing--review and editing, Y.H. and S.P.; supervision, J.G.; funding acquisition, J.G. All authors have read and agreed to the published version of the manuscript.  
This research was funded by The Basic Public Welfare Research Project of Zhejiang Province, grant number LGF22E040002 and The Zhejiang Provincial Science and Technology Innovation Program (New Young Talent Program) for College Students, grant number 2023R411024.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
I would like to thank Expert [PERSON] for generously sharing his insights.  
The authors declare no conflicts of interest.