Centrifugal Fans - Underlying Technology

Howden has supplied more than 25,000 high integrity centrifugal fans for applications where performance, reliability and maintainability are of paramount importance. For large centrifugal fans, the fundamental technology underpinning the basic design is a critical influence on performance and reliability.

Howden has developed a deep understanding of the mechanical, aerodynamic, and acoustic behaviour of the rotor. Key features of the design programme are:

Stress analysis of the impeller
We analyse the low cycle and high cycle fatigue behaviour to allow us to reduce the potential for crack formation and extend the operating life of the impeller, particularly in a regime of a complex centrifugal fan impeller structure undergoing frequent stop/starts.

Dynamic analysis of the rotor
It is essential that large rotating bodies are supported on a secure foundation otherwise unacceptable vibration levels may occur at site. Such problems are notoriously difficult to solve. Our knowledge of rotor dynamics allows us to model the complete support system from soil to shaft, minimising the chance of these problems appearing.

Aerodynamic analysis of impeller flow
Poor flow through the fan impeller will result in loss of output and increases in absorbed power and noise generation. Our modelling techniques are backed up by computational fluid dynamics (CFD). This allows the flow to be optimised, particularly at the junction of the stationary inlet cone and the rotating inlet ring where the gas flowing through the impeller has to undergo an abrupt change in velocity.

Aerodynamic analysis of flow control systems
Using adjustable vanes in the impeller inlet to control the output can, if applied incorrectly, disturb the flow in the impeller and lead to aerodynamic or mechanical disturbances. Our inlet vane control systems have been designed to avoid these problems.

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