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Centrifugal Fan Performance Characteristics

Sep 04, 2017

Centrifugal fans rely on the input of mechanical energy, to improve the gas pressure and send the gas to the machinery, it is a driven fluid machinery. Centrifugal fans are widely used for ventilation, dust and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induced winds for boilers and industrial furnaces; cooling and air conditioning equipment and household appliances Ventilation; grain drying and selection; wind tunnel and hovercraft inflatable and propulsion.

Centrifugal fan is based on the principle of kinetic energy conversion to potential energy, the use of high-speed rotation of the impeller to accelerate the gas, and then slow down, change the flow, the kinetic energy into potential energy (pressure). In a single stage centrifugal fan, the gas enters the impeller from the axial direction, the gas flows into the radial direction through the impeller, and then enters the diffuser. In the diffuser, the gas changes the direction of flow and increases the area of the duct to slow down the airflow, which translates kinetic energy into pressure energy. The increase in pressure mainly occurs in the impeller, followed by the expansion process. In a multistage centrifugal fan, use a refluxor to allow the airflow to enter the next impeller, creating a higher pressure.

Centrifugal fan working principle and turbine compressor is basically the same, are due to low gas flow rate, pressure change is not, generally do not need to consider the gas specific volume changes, that is, the gas as incompressible fluid treatment.

Centrifugal fans can be made of two types of right and left. From the motor side of the face: the impeller clockwise rotation, known as the right rotating fan; impeller counterclockwise rotation, known as the left rotating fan.

Features: Centrifugal fan is a variable flow constant pressure device. When the speed is constant, the pressure-flow curve of the centrifugal fan should be a straight line, and the actual characteristic curve is curved due to internal losses. The pressure generated in the centrifugal fan is greatly influenced by changes in the inlet temperature or density. For a given intake air volume, the highest inlet air temperature (lowest air density) produces the lowest pressure. For a given pressure and flow characteristic curve, there is a power and flow characteristic curve. When the blower runs at constant speed , The required power increases for a given flow rate as the intake air temperature decreases

Fault repair: centrifugal fan drive parts wear is often the equipment problems, including the exhaust fan bearing, bearing chamber wear, blower shaft bearing wear and so on. For the centrifugal fan failure, the traditional maintenance methods are surfacing, thermal spraying, brush crossing, but there are some disadvantages: welding heat generated by high temperature can not be completely eliminated, easy to cause material damage, resulting in parts bending or fracture; The brush plating by the coating thickness limit, easy to peel off, and the above two methods are metal repair metal, can not change the "hard to hard" with the relationship, in the combined effect of each force, will still cause the drum Wear again. Contemporary Western countries for the above problems and more use of polymer composite materials repair methods, and the application is more of the United States blessing blue technology system, which has a strong adhesion, excellent compressive strength and other comprehensive performance, Processing. There is no effect of welding thermal stress, repair the thickness is not restricted, while the product has a metal material does not have the concession, can absorb the impact of equipment shock, to avoid the possibility of re-wear, in the country for centrifugal fan repair applications Also gradually replace the traditional method.