What is the role of the stationary case around the impeller in a supercharged engine?

• A. It surrounds the impeller and helps collect the flow, converting velocity into pressure.
• B. It forms the combustion chamber.
• C. It vents exhaust gases.
• D. It acts as a cooling jacket.

Answer: (A)

In a supercharged setup, the impeller increases the air’s velocity and energy, but the stationary casing around it serves as a diffuser. This surrounding housing surrounds the impeller and guides the flow into a diffuser path, slowing the high-velocity air and converting its kinetic energy into static pressure. By doing this, the pressure of the air leaving the compressor is raised efficiently before it enters the engine, and the flow is made smoother for the next stage or intake.

This role isn’t about forming a combustion chamber, venting exhaust, or acting as a cooling jacket, which are functions of other engine systems.