Contra-Rotating Two-Stage Axial Impellers

A contra-rotating system consists of two single stage opposite handed impellers rotating in opposed directions.

Compared to a single stage system

• The contra-rotating system develops approximately 2-3 times the static pressure of a single stage impeller system of the same diameter and speed.
• The two-stage system uses 5-10% less power and is quieter than a single stage system producing the same work at the same diameter.
• A two-stage system delivers a parallel non turbulent air stream, contrary to a single stage impeller which has a rotating turbulent air stream.

In operation

The air flow can be regulated by idling one stage. A flow reduction of 35% and a power reduction of 50% is possible without losses.
If necessary more stages can be added if pressure demands are higher than a two-stage system can meet.

Selection

The selection of the two axial impellers is based upon the Multi-Wing standard range which offers many possible combinations. The Multi-Wing Optimiser selection programme produces customised performance curves at any rpm, diameter and power consumption within the Multi-Wing impeller system. This information is based upon a large number of practical tests in the Multi-Wing Wind Tunnel.