Which statement best describes how a dual axial-flow compressor improves turbojet efficiency?

Which statement best describes how a dual axial-flow compressor improves turbojet efficiency?

• A. The system uses fewer moving parts
• B. Higher compression ratios can be obtained
• C. It reduces weight
• D. It lowers fuel consumption

Answer: (B)

The essential idea is about boosting the pressure rise that the compressor can deliver. A dual axial-flow compressor lets air pass through two separate axial paths, each optimized for efficient compression, so you can achieve a higher overall pressure ratio than with a single-path design. That higher compression ratio improves the Brayton cycle efficiency of the turbojet, meaning more thrust per unit of fuel or the same thrust with less fuel. So the best way to describe the improvement is that it enables higher compression ratios. The other points aren’t the primary mechanism: the dual flow setup doesn’t inherently reduce moving parts or guarantee lighter weight, and while higher efficiency can lead to lower fuel use, that’s a downstream result rather than the direct mechanism.

The essential idea is about boosting the pressure rise that the compressor can deliver. A dual axial-flow compressor lets air pass through two separate axial paths, each optimized for efficient compression, so you can achieve a higher overall pressure ratio than with a single-path design. That higher compression ratio improves the Brayton cycle efficiency of the turbojet, meaning more thrust per unit of fuel or the same thrust with less fuel. So the best way to describe the improvement is that it enables higher compression ratios.

The other points aren’t the primary mechanism: the dual flow setup doesn’t inherently reduce moving parts or guarantee lighter weight, and while higher efficiency can lead to lower fuel use, that’s a downstream result rather than the direct mechanism.