## 3 Results and Discussion
### Effects of Fire Locations
To better evaluate the smoke flow in a uniform lateral opening stairwell, Figure 9 was obtained from the simulation data of the stairwell model with the opening at each floor. Moreover, Figure 9-e differ with respect to the location of the fire source. The smoke was found to mainly flow in the stairwell above the fire source. This phenomenon is due to the difference between the air density and thermal smoke density, i.e., the pressure difference between the air and thermal smoke. It is, therefore, safer for a person to be situated downstairs in the stairwell after the initiation of the fire. Moreover, this makes it necessary for people to lean forward when evacuating a fire disaster. Figure 8: Velocity vector fields at x = 8.5 m at different fire locations (fire located at Floors 1, 5, and 15) with a fire HRR of 1.5 MW. As discussed above, the temperature distribution in the stairwell is mostly due to the thermal smoke flow. An increase in the smoke flow in certain areas leads to an increase in temperature. To quantify the impact of thermal smoke flow, the data collected by the thermocouples during the simulation in which the fire HRR was 1.5 MW were further evaluated. Herein, the fire location factor \(h^{*}\) was defined as the relative location of the fire source in the entire building, which can be expressed as follows:  
\[h*=h/H \tag{7}\]  
where \(h^{*}\) is the fire location factor, \(h\) is the height of the fire source, and \(H\) is the total height of the building (H = 89.3 m). Table 5 presents the detailed data obtained from the simulation results by changing the fire location. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Test**} & \multirow{2}{*}{**Fire Location**} & \multirow{2}{*}{\begin{tabular}{c} **Fire Location** \\ **Factor** \\ **\(h\) (m)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Maximum** \\ **Factor** \\ **\(h^{*}\)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Time Required to** \\ **Temperature of** \\ **Measuring Points** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Height of** \\ **Reach Maximum** \\ **Temperature** \\ **Temperature** \\ **\(t_{m}\) (s)** \\ \end{tabular} } \\ \hline
1 & 0.2 & 0.002 & 145 & 91 & 1.5 \\
2 & 6.0 & 0.067 & 143 & 58 & 8.4 \\
3 & 10.8 & 0.121 & 143 & 62 & 13.0 \\
4 & 19.5 & 0.218 & 142 & 60 & 21.5 \\
5 & 27.6 & 0.309 & 141 & 56 & 29.6 \\
6 & 31.7 & 0.350 & 140 & 54 & 33.8 \\
7 & 40.0 & 0.448 & 136 & 58 & 41.9 \\
8 & 48.1 & 0.539 & 133 & 62 & 50.2 \\
9 & 60.5 & 0.677 & 125 & 55 & 62.5 \\
10 & 68.6 & 0.768 & 123 & 49 & 70.7 \\
11 & 76.8 & 0.860 & 120 & 50 & 78.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Maximum temperature of measuring points at different heights. Figure 9: Smoke flow at different fire source locations (Floors 1, 5, 10, 15, and 20) and at an HRR of 1.5 MW. The scattered data in Figure 10 were obtained from the third and fourth columns of Table 5, which illustrate the relationship between the maximum temperature and fire source location. A linear relationship was found between the maximum temperature and the fire source location [16], which could be fitted using the least squares method, and it is indicated by the red line in Figure 10. Moreover, it can be expressed mathematically by Equation (8):  
\[T_{m}=-30.5\times h^{*}+147.7 \tag{8}\]  
Hence, as can be seen from Equation (8) and Figure 8, at the same fire HRR, changes in the height of the fire source led to changes in the maximum temperature, i.e., with a decrease in the fire location factor or height of the fire source, there was a linear decrease in the maximum temperature in the stairwell. This can be explained by the smoke flow and buoyancy plume. In the final section, Figure 10 reveals that the thermal smoke moves upward under the influence of the buoyancy plume. Therefore, there was a decrease in the space above the thermal smoke in accordance with an increase in the height of the fire.