Axial Fans
Unlike centrifugal fans consisting of rotating impellers that create perpendicular air flow, axial fans cause air to move in a parallel, or linear, direction. These two fan types come in low, medium and high pressures, though centrifugal fans can generate much more pressure (about four times) at the same rotational speed due to their "churning" perpendicular air flow, which is utilized in leaf blowers, blowdryers, air mattress inflators, etc. Axial fans are able to move large amounts of air at high rates, operating optimally as cooling, ventilation, exhaust and duct fans in lower pressure environments. The rotating impeller unit of a centrifugal fan has the appearance of a hamster's exercise wheel, while an axial fan has curved or angled blades that make a circular form around the axis of rotation. People know axial fans as their oscillating electronic household fans. A tube axial fan consists of only the propeller blades inside a cylindrical housing; however, vane axial fans have straightening vanes attached to the interior fan housing that reduce turbulence for highly efficient air flow.
From small axial cooling fans within laptops to huge wind tunnel axial fans used to test and measure aerodynamic forces, these devices have numerous home, commercial and industrial functions. Maybe the most visible and familiar type of axial fan is the ceiling fan; however, axial fans keep many important things cool. Without an axial cooling fan, car engines would be overheating repeatedly and sensitive computer equipment wouldn't be kept at a safe temperature. Axial ventilation fans or axial exhaust fans are used in HVAC systems to circulate air and keep it fresh as it moves through the duct work air tunnels. These axial blowers exhaust fumes, smoke and dust; remove excess heat and gases; and transfer heated or cooled air throughout large buildings. They are utilized in systems for clean room aeration, tunnel ventilation and parking garage exhaust, and can be configured with sound trapping housings.
Axial fans are driven by belts and pulleys, AC motors or DC motors. Computer equipment cooling fans require brushless DC motors because they produce a significantly lower amount of electromagnetic interference. When fans operate within machines powered by a motor, as in cars, boats and cooling systems, the fan is often connected to this, either directly to the drive shaft or by a belt and pulleys. A fan may be mounted on one shaft of a dual-shaft motor to cool the motor itself.