How is the compression ratio of an axial flow turbine engine calculated?

The compression ratio of an axial flow turbine engine is indeed calculated by comparing the discharge pressure of the last stage of compression with ambient air pressure. This is a critical metric because it provides insight into the engine's efficiency and performance. The compression ratio indicates how much the air is compressed before it enters the combustion chamber.

In axial flow engines, air flows through multiple stages of rotating and stationary blades, which increase the pressure and temperature of the air. The discharge pressure from the last stage of compression represents the high-pressure air that is ready for combustion, while ambient air pressure serves as a baseline for comparison. This ratio reflects the engine’s ability to compress air effectively, which is essential for optimal thrust and fuel efficiency.

While the other options may involve calculations or parameters relevant to engine performance, they do not accurately represent how the compression ratio is defined or calculated in the context of axial flow turbine engines. For example, option A relates to measuring pressure differentials that are not directly correlated with compression ratio. Option C focuses on temperature measurements which do not provide a direct ratio of pressures required for defining compression ratio. Lastly, option D compares flow rates rather than pressure, which also does not pertain to the calculation of compression ratio. Thus, the comparison of the discharge pressure