## 2 Ship Fire Simulation
### Analysis of Simulation Results  
In the case of a cabin fire, the main study of the disaster process of ship fire, and referring to the appendix of the \"Ship Alternative Design and Layout Application Guide\" [15], the life safety performance of the criteria parameters include the critical danger value of toxic gas, hot gas' shading level, and high temperature [19]. The position of the evaluation point is selected as the 1.8 m height of the personnel evacuation area (tower column stair entrance, evacuation passage, etc. ), as shown in Table 1.  
The analysis shows that the hazards of cabin fire mainly include the generation of toxic and harmful gasses, the lack of oxygen in the high-temperature combustion environment, and the reduction in visibility due to the generated smoke [20]. In order to study the \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Limit Value** \\ \hline
1.8 altitude temperature (\({}^{\circ}\)C) & 60 \\
1.8 m high visibility (m) & 10 \\
1.8 m high CO concentration(ppm) & 500 \\
1.8 m high CO\({}_{2}\) concentration(ppm) & 10,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Danger approaching time control judgment index. Figure 3: Setting of model external environment parameters. Figure 2: Distribution of measuring points in the cabin. situation when the fire occurs, the numerical simulation is carried out by setting CO detector, temperature, smoke, and visibility detection slices so as to better analyze. At a height of 1.8 m from the bottom cabin, the sections of CO concentration, visibility, and temperature at different times are shown in Figure 4 to observe the spread of engine room fire smoke [17]. 1. As can be seen from the CO concentration change chart at a height of 1.8 m, within 1200 s of the simulation time, the CO concentration at a height of 1.8 m in the cabin locally rose to 50 ppm, far less than the critical value of CO concentration. 2. As can be seen from the visibility change chart at a height of 1.8 m, when the simulation time reaches 100 s, the visibility at a height of 1.8 m in the cabin decreases to a large area of about 15 m, which is still within the safe range; at 200 s, the visibility at a height of 1.8 m in the cabin was reduced to 10 m, and the visibility change reached a critical danger value. Moreover, due to the complex structure of the equipment in the cabin, the smoke gathered between the equipment and further reduced visibility. At 400 s and beyond, visibility in the cabin at 1.8 m is below the critical threshold. Therefore, the rescue time under the influence of visibility in the cabin is 200 s.
3. As can be seen from the temperature variation chart at a height of 1.8 m, due to the small size of the oil pool fire, only the local high temperature appeared above the fire source at 100 s, and the overall temperature of the engine room was low and did not reach the critical danger value. With the development of the fire, the high temperature began to spread around. When the simulation time reached 200 s and  
Figure 4: Changes of 1.8 m CO.  
later, the temperature of 1.8 m above the ground in the engine room basically reached the critical temperature of danger, and the ultra-high temperature of 120 \({}^{\circ}\)C appeared above the oil pool, which would cause harm to the surrounding structure. Therefore, the rescue time under the influence of cabin temperature is 200 s.  
In the process of heptane oil pool fire, combustion will produce a variety of harmful gasses, including carbon monoxide (CO): When heptane is not completely burned, carbon monoxide may be produced, which is a colorless and odorless toxic gas that is highly dangerous to the human body. Carbon dioxide (CO\({}_{2}\)): When completely burned, heptane produces carbon dioxide. Although carbon dioxide itself is not a direct poison gas, at high concentrations it can cause hypoxia and suffocation.