Centrifugal fan blade impeller rotating between the gas, the kinetic energy obtained by the centrifugal force (dynamic pressure) discharged from the peripheral impeller, volute-shaped casing through the guide, so that the fan exit flow, resulting in the center of the impeller the formation of negative pressure, air flow into the external complement, so that fans can exhaust gases.
Through the shaft to the motor power to the fan impeller, the impeller energy transfer to the air, the air under the action of the rotation produces centrifugal force, the extension of the air fan impeller blades to spread around this time, the greater the impeller, the energy received by the air the greater is the fan pressure head (pressure) increases. If the large wheel cut is small, does not affect the air flow, will reduce the pressure.
Centrifugal fan impeller and the casing formed mainly by the small fan impeller mounted directly on the motor, the large fan and motor by coupling or pulley connected. Centrifugal fan inlet is generally unilateral, with a single-stage impeller; flow inlet can be bilateral, with two back to back of the impeller, also known as double-suction centrifugal fan.
The main component is the fan impeller, its geometric shape, size, leaf number and manufacture of precision have a significant impact on performance. Static balance impeller or fan balancing correction to ensure smooth rotation. Export by leaves of different direction, the impeller is divided into forward, three types of radial and backward. Prior to the impeller blades at the top of the impeller rotation direction of the tilt; radial impeller blades at the top to the radial direction, is divided into straight and curved blade-shaped leaves; after the impeller blades to the top of the impeller rotating reverse tilt .
Before the maximum pressure generated by the impeller, the flow rate and a certain number of revolutions, the minimum required diameter of the impeller, but the efficiency is generally low; after contrast to the impeller, the pressure generated by the minimum, maximum impeller diameter required, and the efficiency is generally higher ; radial impeller in between. A straight line blade-type leaves most simple, most complex wing-shaped leaves.
In order to have the right blade surface velocity distribution, the general curve-shaped leaves, such as the thickness of the arc leaves. Impeller usually have a cover plate to increase strength and reduce the impeller blades and the chassis between the gas leak. Blade and cover plate with welded or riveted connection. Welded impeller lighter, smooth flow. Low, medium small centrifugal fan impeller has aluminum casting.