How long can the inner wall of the BEA withstand a flame of 2000 degrees?

The inner wall of the Boundary Expansion Area (BEA) is designed with materials that can tolerate high temperatures, such as those generated by a flame reaching up to 2000 degrees Fahrenheit. In typical turbine systems, materials used in the construction of components like the BEA are selected based on their thermal resistance and durability under extreme conditions.

In this context, the specific endurance time for the inner wall at 2000 degrees is typically tested and established through engineering standards and material properties. The given choice of 15 minutes reflects a realistic duration for the inner wall to maintain integrity under such intense thermal conditions without suffering catastrophic failure. This time frame accounts for the material's thermal characteristics alongside cooling mechanisms that may be integrated into the system to manage heat load effectively.

The other options suggest longer durations that would not align with typical material limits or industry standards for components subjected to direct flame exposure. Hence, the choice of 15 minutes is supported by practical engineering data concerning material performance against prolonged exposure to extreme heat.