What are the stator blades for in a centrifugal compressor?

• A. The stator blades accelerate air
• B. The stator blades act as diffusers at each stage, partially converting high velocity to pressure
• C. The stator blades cool the gas
• D. The stator blades supply fuel to the combustion chamber

Answer: (B)

Stator blades are stationary vanes placed after the impeller in a centrifugal compressor. Their job is to straighten the swirling flow produced by the rotor and to slow the gas down, which converts the excess velocity into static pressure. In effect, they act as diffusers at each stage, recovering part of the kinetic energy and directing the flow into the next impeller with the proper direction and angle. They do not accelerate the gas—that’s the rotor’s role, nor do they cool the gas or supply fuel. This diffuser action is what raises the pressure from stage to stage and helps maintain efficient, smooth flow through multiple stages.