## 3 Result and Discussion  
### Analysis of Maximum Pressure and Maximum Pressure Rise Rate  
Figure 7 shows the variations in the maximum explosion pressure and pressure-time histories along the X-, Y-, and Z-axes as a result of the the ignition position. The maximum explosion pressure was defined as the peak pressure recorded during the combustion process. It exhibited an evident dependence on the ignition location. Along the X-axis, the maximum pressure of 4.16 bar was observed at the central position (6.1 m), whereas lower values of 3.78 bar and 3.83 bar were obtained near the port side wall (0.1 m) and starboard side wall (9.9 m), respectively. This trend indicates that ignition near the walls resulted in reduced explosion intensity. This is presumably due to energy dissipation and interference from the reflected pressure waves. A similar distribution was observed along the Y-axis. The central region (7.5 m) produced the highest pressure of 4.18 bar. By contrast, a significantly lower pressure (3.24 bar) was measured near the forward wall (14.9 m). The consistent pattern observed along both axes indicates that a symmetrical flame propagation characteristic originating from the centre contributes to higher peak pressures. In the Z-axis \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Monitoring Point**} & **Position** & **Position** & **Position** \\  & **X Axis (m)** & **Y Axis (m)** & **Z Axis (m)** \\ \hline
1. & 0.1 & 0.1 & 4.9 \\
2. & 0.1 & 14.9 & 4.9 \\
3. & 9.9 & 0.1 & 4.9 \\
4. & 9.9 & 14.9 & 4.9 \\
5. & 0.1 & 0.1 & 0.1 \\
6. & 0.1 & 14.9 & 0.1 \\
7. & 9.9 & 0.1 & 0.1 \\
8. & 9.9 & 14.9 & 0.1 \\
9. & 5.0 & 7.5 & 4.9 \\
10. & 5.0 & 7.5 & 2.5 \\
11. & 5.2 & 7.5 & 0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Arrangement of monitoring points in FPR for 3D explosion simulation. Figure 6: Arrangement of monitoring points in FPR. direction, the highest pressure (4.27 bar) occurred near the ceiling (4.9 m), whereas the lowest pressure (4.14 bar) was recorded at 3.1 m. The increased pressure near the ceiling can be attributed to structural characteristics that facilitate the accumulation of combustion gases in the upper space. Specifically, the ignition initiated near the ceiling resulted in a higher maximum pressure owing to the accumulation of hot combustion products and reflected pressure waves in the upper region. This structural confinement enhances the pressure build-up because the combustion gases are trapped near the top of the enclosure. These results imply that ignition at the central or upper locations promotes stronger and more uniform explosions. In contrast, near-wall ignition generates a lower explosion strength owing to asymmetric flame spread and boundary-induced effects. The maximum pressure rise rate (MPRR; defined as the rate of pressure increase from the ignition point to the peak pressure) is an essential indicator of the explosion severity and combustion rate. Figure 8 shows the MPRR distributions at various ignition locations. For the X-axis, ignition at the centre (6.1 m) resulted in the highest MPRR of 2.06 bar/s, whereas lower rates of  
Figure 7: Variation in maximum pressure at different ignition positions. (**a**) Maximum explosion pressure along the X-axis. (**b**) Maximum explosion pressure along the Y-axis. (**c**) Maximum explosion pressure along the Z-axis. 1.40 bar/s and 1.41 bar/s were observed at 0.1 m and 9.9 m, respectively. This demonstrates that central ignition promotes rapid and symmetrical combustion development. Along the Y-axis, the highest MPRR of 2.08 bar/s occurred at 5.5 m, and the lowest value of 1.11 bar/s was recorded near the forward wall (14.9 m). The reduction in the MPRR near the wall reflects delayed flame propagation and weaker combustion dynamics in these regions.