Why are more than two stages not practical for centrifugal-flow compressors?

Why are more than two stages not practical for centrifugal-flow compressors?

• A. Losses in turns between stages
• B. High manufacturing cost
• C. Excessive noise
• D. Poor efficiency at high RPM

Answer: (A)

In a centrifugal-flow compressor, each stage pushes air outward and then directs it into the next stage through interstage ducts and diffusers. To go from one stage to the next, the flow has to be redirected, which creates turning losses. Friction, boundary-layer development, and flow separation in the turns convert some of the useful energy into heat and turbulence, reducing the pressure rise you can gain per stage. As you add more stages, these interstage losses accumulate, so the extra stages provide diminishing returns and make the overall machine less practical. While cost, noise, and high-speed operation matter, the main limiting factor is the energy lost in turns between stages.

In a centrifugal-flow compressor, each stage pushes air outward and then directs it into the next stage through interstage ducts and diffusers. To go from one stage to the next, the flow has to be redirected, which creates turning losses. Friction, boundary-layer development, and flow separation in the turns convert some of the useful energy into heat and turbulence, reducing the pressure rise you can gain per stage. As you add more stages, these interstage losses accumulate, so the extra stages provide diminishing returns and make the overall machine less practical. While cost, noise, and high-speed operation matter, the main limiting factor is the energy lost in turns between stages.