The diffuser is primarily used to increase the static pressure of the air entering the system.

• A. Increase kinetic energy
• B. Create swirl
• C. Increase static pressure
• D. Cool the air

Answer: (C)

Diffusers slow the incoming air to raise its static pressure before it reaches the compressor. By decelerating the flow, kinetic energy (dynamic pressure) is converted into static pressure, so the air enters the engine with a higher pressure while its velocity decreases. This higher intake static pressure reduces the work the compressor must do and improves flow quality. It is not about increasing velocity or swirling the flow, and it’s not a device for cooling the air. That’s why the primary function is to increase static pressure.