What is an Impeller?

Impeller is a mechanical device which is used to move a fluid or air to an intended direction at an angle to the incoming source. An impeller is opposite to turbine which increases fluid pressure and flow of fluid while on the other hand a turbine extracts energy from the fluid by reducing its pressure. Impeller is often housed into a confined ducted space (termed as pump housing) which allows the fluid to be funneled to a particular direction

Impellers Designs

Here we will take a look at two types of impeller designs;

  • Impeller Design - Centrifugal
  • Impeller Design - Axial

Impeller Design - Centrifugal


Airfoil has the highest efficiency and low noise among the centrifugal impeller designs with 9 to 16 blades of airfoil outline curved away from the direction of the rotation. The fluid leaves the impeller at a velocity less than its tip speed. As fluid approaches the blade’s leading edge, the stream splits and travels above and below the blade. The fluid is deflected across the convex curve along the top of the blade and along the flat or concave curve on the bottom of the blade, and flows downward over the sharp trailing edge as it leaves the blade.

Airfoil Applications

Primary application includes
  • General HVAC Systems
  • Industrial Applications as Clean Air Provider

Backward Inclined or Backward Curved

This is slightly less efficient design than airfoil, backward curved impeller generally has lower number of longer blades curved away from the direction of rotation and curved backward from inner edge to outer edge relative to the direction of rotation.