comparison of centrifugal fans based on fan orientation and drive mechanisms

by:AIRWOLF     2020-06-14
A centrifugal fan is a mechanical device used to move air or gas.
Fan wheels mounted on the hub inside the housing help with this movement.
The fan wheel is rotated by an external force (motor or internal combustion engine.
The fan consists of blades or ribs arranged around the hollow hub.
The air or gas to be moved enters the housing through the side of the fan wheel, enters the hollow hub, and then rotates 90 degrees to flow through the fan blade.
The rotating fan then accelerates the air by applying centrifugal force to the air, hence its name.
The accelerated air or gas is then discharged from the housing.
These fans are able to move air with increased pressure, making them ideal for use in pollution control systems, central cooling or heating systems, and blade blowers in inflatable structures.
In addition, by installing the fan on the radiator, plus metal fins, high cooling capacity can be achieved on a small scale.
There are various types of centrifugal fans, classified according to the direction of the fan blade and the driving mechanism of the blade.
Fan blade orientation: Based on AMCA standard 99-2406-
83, the centrifugal fan can be divided into three basic blade positioning methods and further subdivided
Classification based on blade type: the radial Blade fan is composed of blades extending outward and extending directly from the hub.
These radial fans are characterized by high pressure, high speed and low volume airflow.
These features make them suitable for pneumatic conveying systems and vacuum cleaners.
This type of blade is less sensitive to solids and is usually used for particles-
Streams full of gas
While radial tip blades achieve up to 83% efficiency by reducing gas turbulence, open radial blades with overload power features allow the addition of wear plates in larger grinding applications. Backward-
The fan blade in this type of fan is tilted backwards relative to the rotation direction of the fan.
In addition, these types of fans are divided into three types: flat blades, curved blades, and wing blades.
The curved and parallel blades are able to handle the airflow containing fine air particles that usually damage the design of the wing.
Flat blades can also be modified to reduce instability compared to curved blades and provide efficiency of 77 to 80%.
On the other hand, wing blades provide better operational efficiency from 84 to 91%.
These blades are usually used in systems with low or medium loads.
A curved fan with a higher specific speed is more effective than a radial blade and is usually used for medium flow, high
Pressure application.
None of the three backward-leaning blades
Overload characteristic.
Lower noise emissions and higher stability in parallel operation make these backward tilting blade fans a better choice for most applications. Forward-
In this type of fan, the blades are oriented, so they tilt forward in the same direction as the fan rotates.
Depending on the geometry of the blades, these fans can be further divided into flat and curved fans.
Forward curved blades are able to provide greater static pressure and air volume than the wing backward blades.
The forward curved blade fan operates at a lower speed and is especially suitable as a small fan for the ventilation system.
While the blades bent backward are more effective, the blades bent forward show \"self
Cleaning \"features, the fact that they are used in applications with high dust concentrations, or in systems where air-conveying materials are used.
Drive mechanism: the drive of the centrifugal fan solves the speed of the fan wheel and its limit of change.
According to its drive mechanism, the fan can be divided into direct drive, belt drive and variable drive.
Drive this type of fan directly, the wheel is directly connected to the shaft of the motor, ensuring that the speed of the wheel is the same as the speed of the motor.
In this way, the speed of the fan can be adjusted by controlling the speed of the motor.
This type of drive mechanism results in a compact fan system with stable RPM.
The belt drives this type of fan, with a set of pulleys installed on the motor shaft and the fan axle.
A belt that transmits electricity, connecting two pulley sets.
The ratio of the motor pulley diameter to the wheel diameter determines the speed of the fan wheel.
The use of this type of drive mechanism ensures a fixed fan speed until the belt slips.
This type of drive mechanism typically uses magnetic or hydraulic coupling to control the fan speed.
This type of drive allows the user to control the fan speed independently of the motor speed.
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