What is the function of the diffuser section?

• A. Heats the air
• B. Filters debris
• C. Increases velocity of air into combustor
• D. Slows down and evenly spreads out the compressor discharge air for combustion

Answer: (D)

The diffuser’s job is to slow the high-velocity air coming from the compressor and raise its static pressure so it can enter the combustor smoothly. By expanding the duct, it converts some of the air’s kinetic energy into pressure, reducing velocity and creating a uniform flow across the combustor inlet. That even distribution helps fuel mix well and burn cleanly, leading to stable combustion and fewer hotspots or flow irregularities. It’s not about heating or filtering the air, and it doesn’t increase velocity—the diffuser deliberately decelerates and evenizes the flow for efficient combustion.