What is an axial fan? Features, structure and usage

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What is an axial fan?

An axial fan is a fan in which the motor is placed on the frame that supports the entire fan, and the blades are placed around it. When viewed from the label side, the blades rotate clockwise or counterclockwise. In the case of the fan shown in Figure 1, air is sucked in from behind the label and expelled to the front. In this way, the direction of the air flow is the same as the direction of the central axis of the rotating blades, so it is called an axial fan.

Figure 1: Structure of an axial fan

DC axial fans and AC axial fans have different structures.

▲Figure 2: Differences in structure between DC axial fans and AC axial fans

Characteristics of an axial fan

Axial fans have an airflow-static pressure characteristic (P-Q performance) as shown in Figure 3. As the airflow rate increases, the static pressure decreases, resulting in a rightward sloping characteristic. Another characteristic of axial fans is the appearance of a "swirl stall region" where the slope changes significantly in the middle of the fan.

The rotating stall region is the region where stall begins to occur. At maximum airflow, the air flows smoothly along the surface of the blade, but as the static pressure increases, the air starts to flow away from the surface of the blade. This state is called stall.

In the rotating stall region, the air flows over the surface of the blades and then repeatedly separates, creating an unstable state. At this point, power consumption and sound pressure levels change significantly.

How to use an axial fan effectively

Axial fans come in a wide lineup with features such as high airflow, high static pressure, and low noise, and are used in a variety of applications such as ventilation, localized cooling, etc.
When installing an axial fan in a device, it is possible to reduce the noise and power consumption of the device by setting the fan's operating point on maximum airflow side, with the rotating stall region as the boundary, so we encourage you to try putting what you have learned into practice.

Supervised by: SANYO DENKI CO., LTD. Cooling System Design Department

Update date: 2023-05-19 00:00 /release date: 2019-01-08 00:00