Features of Counter Rotating Fan

Last time we introduced axial fans. This time we will explain about Counter Rotating Fan which are a special type of axial fan.

What is Counter Rotating Fan?

Counter Rotating Fan is a fan that has a structure similar to two axial fans connected in series. The front stage (the fan that draws in air) and the rear stage (the fan that expels air) have blades that rotate in different directions, so if the front stage rotates counterclockwise, the rear stage rotates clockwise.
Structurally, it may appear that it is simply two axial fans connected in series, but simply connecting two identical axial fans in series will not achieve the same performance as Counter Rotating Fan.

▲Figure 1: Structure of Counter Rotating Fan

When two axial fans with the same rotation direction are connected in series, the blades in the rear stage swirl the swirling air from the front stage even more strongly before expelling it, causing the air to spread out.
On the other hand, in the case of Counter Rotating Fan, the rear blades rotate in the opposite direction, weakening the swirling flow of the air from the front, and creating a straight air flow.

▲Figure 2: Image of air flow

The performance of Counter Rotating Fan changes dramatically depending on the combination of front and rear blades.
SANYO DENKI CO., LTD. 's Counter Rotating Fan are designed with maximum consideration given to air volume, static pressure, noise and lifespan.

Characteristics of Counter Rotating Fan

Counter Rotating Fan maximum airflow In the 8th hour, we learned that the swirl stall region, which is an unstable condition where the air flows cleanly or swirls repeatedly on the surface of the blades, exists near the middle of P-Q performance. Counter Rotating Fan, but the swirl stall region of the vane is in the range where P-Q performance flattens out.

Specific usage of Counter Rotating Fan

Counter Rotating Fan The optimal range of use is wide because the swirl stall region is located to the left on P-Q performance. It can send out air without being defeated by obstacles, even for equipment with high ventilation resistance.
In other words, it is suitable for cooling small devices with high mounting density or cooling objects by direct airflow. It can also be used to send wind over a long distance.

We will introduce some specific use cases.

Customer Case Study on 1U Server

assignment:

In order to achieve high density mounting in a 1U server, it is necessary to improve cooling efficiency.

Even when two small fans were installed in series, the required static pressure could not be obtained, and installing them in parallel was also abandoned due to lack of space.

A cooling fan with high airflow and high static pressure that can fit into a limited space is required.

Air Suspension Conveyor Customer Cases

assignment:

Air levitation conveyors require fans capable of levitating large glass substrates.

Since hundreds of conveyors will be installed, it is important to reduce the power consumption of the fans.

Since the system will be installed near a quiet clean room, it is important to keep fan noise to a minimum.

Above we have explained Counter Rotating Fan.
SANYO DENKI CO., LTD. offers a lineup of fans in various sizes, including Counter Rotating Fan, that can help solve problems with your equipment.

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

release date: 2020-09-16 00:00

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