## 2 Methodology
### Material Properties and Boundary Conditions
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Therophysical Property** & \multicolumn{2}{c}{**Value**} \\ \hline \(V_{f}\) & \multicolumn{2}{c}{0.61} \\ \hline \(\rho\) (kg/m\({}^{3}\)) & \(\rho_{f}\) & 1810 \\ \cline{2-3}  & \(\rho_{r}\) & 1200 \\ \hline \(C\) (J/kg\(\cdot\)K) & \(C_{f}\) & 931 + 3.47 T \\ \cline{2-3}  & \(C_{r}\) & 750 + 2.05 T \\ \hline \(k\) (W/m\(\cdot\)K) & \(k_{\Omega}\) & 2.4 + 5.07 \(\times\) 10\({}^{-3}\) T \\ \cline{2-3}  & \(k_{\Omega}\) & 7.69 + 1.56 \(\times\) 10\({}^{-2}\) T \\ \cline{2-3}  & \(k_{r}\) & 0.148 + 3.43 \(\times\) 10\({}^{-4}\) T \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Thermophysical properties of materials constituting CFRP. Figure 4: Cross-sectional view of boundary conditions for heat transfer simulation: (**a**) spar-cap manufacturing process; (**b**) contact heat conduction of the interface between spar-cap and mold. because the scale difference is so large. However, the model used in this simulation has a minimum thickness of 5 mm and a maximum length of 3 m, so the macroscopic and microscopic properties of the composite must be implemented together. Therefore, the thermophysical properties of the fine fiber structure of the composite material have been simplified. CFRP, which is the main component of the spar-cap, has different thermophysical properties depending on the arrangement of fibers. If the fiber arrangement is unidirectional (UD), it can be simplified by using equations such as Equations (9)-(13) [24]. The GFRP mold also determined the thermophysical property values of the composite material mold by the microscopic method of simplifying the fiber structure of the CFRP spar-cap. Table 2 summarizes the thermophysical property values of isotropic materials and fluids used in the heat transfer simulation and the thermophysical property values of the CFRP obtained above. The values of aluminum and copper in Table 2 are constant numbers, which are thermophysical property values at room temperature provided by SC/Tetra. For the thermophysical properties of GFRP, the results of experiments conducted by [PERSON] were applied [25; 26]. The actual blade \(V_{f}\) (fiber volume fraction) of this study was used in Equations (9)-(13). Tables 1 and 2 summarize the results of simplifying thermophysical properties. \[\rho = V_{f}\rho_{f}+\left(1-V_{f}\right)\rho_{r} \tag{9}\] \[C = V_{f}C_{f}+\left(1-V_{f}\right)C_{r}\] (10) \[k_{1} = V_{f}k_{1f}+\left(1-V_{f}\right)k_{r}\] (11) \[k_{2} = k_{3}=k_{r}\left[ \begin{array}{c}\left(1-2\sqrt{\frac{V_{f}}{ \pi}}\right)\\ +\frac{1}{B}\left\{\pi-\frac{4}{\sqrt{1-\frac{B^{2}V_{f}}{\pi}}}tan^{-1}\frac {\sqrt{1-\frac{B^{2}V_{f}}{\pi}}}{1+B\sqrt{\frac{V_{f}}{\pi}}}\right\}\\ B=2\left(\frac{k_{r}}{k_{2f}}-1\right)\end{array} \right.\] (12) \[B = 2\left(\frac{k_{r}}{k_{2f}}-1\right) \tag{13}\]  
Thermal diffusion by convection uses air as a medium. The initial value of air and the standard temperature for certain physical properties is 30 \({}^{\circ}\)C, density \(\rho_{air}=1.164\) kg/m\({}^{3}\), thermal diffusion coefficient \(\alpha_{air}=0.00341\)/K, viscosity coefficient \(\mu_{air}=1.83\times 10^{-5}\) Pa\(\cdot\)S, heat transfer coefficient \(h_{air}=10\) W/m\({}^{2}\cdot\)K, specific heat \(C_{air}=1007\) J/kg\(\cdot\)K, thermal conductivity \(k_{air}=0.0256\) W/m\(\cdot\)K.