In an axial-flow compressor, the purpose of the stator vanes at the discharge end of the compressor is to?

In an axial-flow compressor, the purpose of the stator vanes at the discharge end of the compressor is to?

• A. Increase discharge temperature
• B. Decrease pressure loss
• C. Straighten the airflow and reduce turbulence
• D. Increase swirl

Answer: (C)

The main idea here is that the stator vanes at the discharge of an axial-flow compressor serve to remove the swirl and smooth the flow so it exits in a nearly axial, uniform direction for the next stage. The rotor blades impart a swirling, tangential component to the air; without a stator, that swirl would persist into the next rotor, increasing losses and causing nonuniform loading. The stationary vanes redirect and straighten the flow, reducing turbulence and secondary flow, which improves efficiency and prepares a clean, axial entry for the following stage. Increasing discharge temperature isn’t the goal, and while shaping the flow can influence overall losses, the primary function is smoothing and aligning the flow. Increasing swirl would be counterproductive, which is why the correct choice emphasizes straightening and reducing turbulence.

The main idea here is that the stator vanes at the discharge of an axial-flow compressor serve to remove the swirl and smooth the flow so it exits in a nearly axial, uniform direction for the next stage. The rotor blades impart a swirling, tangential component to the air; without a stator, that swirl would persist into the next rotor, increasing losses and causing nonuniform loading. The stationary vanes redirect and straighten the flow, reducing turbulence and secondary flow, which improves efficiency and prepares a clean, axial entry for the following stage.

Increasing discharge temperature isn’t the goal, and while shaping the flow can influence overall losses, the primary function is smoothing and aligning the flow. Increasing swirl would be counterproductive, which is why the correct choice emphasizes straightening and reducing turbulence.