Blade count

• More blades can deliver smoother airflow and lower tonal fan noise because the pressure pulses are distributed more evenly.

• Fewer blades reduce drag and can improve efficiency at the cost of higher noise tones.

• The sweet spot often depends on the application: quiet comfort in an office space vs maximum cooling in a mining shaft.

Blade pitch

• Steeper pitch moves more air at lower speeds, which can cut fan noise but increase motor load.

• Shallower pitch reduces power consumption but may need higher speeds, often raising noise levels.

• Fine adjustments – sometimes as little as one degree – make a measurable difference in both sound and performance.

Casing design

• Well-designed casings reduce tip vortices, lowering noise and improving efficiency.

• Poor casings or no casings create turbulence, which increases both energy loss and broadband noise.

• In cooling towers or HVAC units, casing geometry often decides whether a system meets regulatory noise limits.

Why fan noise matters

Noise is not just a comfort issue – it’s a regulatory and community concern. At the same time, efficiency drives down energy bills and carbon footprints. By optimising geometry, engineers can design fans that achieve the right balance for each environment, whether that’s silent operation in a hospital or rugged airflow in an industrial plant.

The result: quieter, more efficient fans that meet both performance and compliance demands.