Knowledge of air model fan

Brief introduction of air model fan

Air model fan is the general name of all fans needed for blowing model.

The core air model fan and the axial flow air model fan are separated from the working principle. Centrifugal fan can be divided into high pressure air model fan, medium pressure air model fan and low pressure blower from wind pressure. Axial flow fan is mainly used in air dancing model.

From the material, the air mold fan can be divided into stainless steel air mold fan, plastic air mold fan, cast aluminum air mold fan, cast iron air mold fan and iron sheet air mold fan.

Relationship between air model fan and industrial centrifugal fan

Air model fan is a part of industrial centrifugal fan and kitchen fan.

Air model fan is also called arch fan. Now the most commonly used fans in China are centrifugal fans, and a few of them are axial fans. The dancing star in the air is one of them. In recent years, due to the vigorous development of the air mold industry, the improvement of the air mold fan has been promoted, and gradually to the direction of small volume, large air volume, light weight, easy to carry and so on.

Fan knowledge -- fan

Fan is a kind of driven fluid machinery, which depends on input mechanical energy to improve gas pressure and discharge gas.

Fans are widely used for ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induced air of boilers and industrial furnaces; cooling and ventilation of air conditioning equipment and household electrical equipment; drying and selection of grain; air source of wind tunnel and inflation and propulsion of hovercraft.

The working principle of the fan is basically the same as that of the turbine compressor. However, due to the low gas velocity and small pressure change, it is not necessary to consider the change of gas specific volume, that is, the gas is treated as an incompressible fluid.

Fans have a long history. China has made simple wooden hulling windmills for many years B.C., and its working principle is basically the same as that of modern centrifugal fans. In 1862, guebel invented the centrifugal fan in England. Its impeller and casing are concentric circles, and the casing is made of brick. The wooden impeller adopts backward straight blades, with an efficiency of only about 40%. It is mainly used for mine ventilation. In 1880, cochlear casing and centrifugal fan with backward curved blades were designed for mine ventilation and supply, and their structures were relatively perfect.

In 1892, the cross flow fan was developed in France; in 1898, the Irish designed the Siroco type centrifugal fan with forward blades, which was widely used in various countries; in the 19th century, axial-flow fan had been used in mine ventilation and blast in metallurgical industry, but its pressure was only 100-300 PA, and its efficiency was only 15-25%. It did not develop rapidly until 1940s.

In 1935, Germany first adopted the axial flow constant pressure fan for boiler ventilation and induced air; in 1948, Denmark made the axial flow fan with adjustable moving blade in operation; rotary axial flow fan, meridional accelerated axial flow fan, oblique flow fan and cross flow fan were also developed.

According to the direction of gas flow, fans can be divided into centrifugal type, axial flow type, oblique flow type and cross flow type.

When the centrifugal fan works, the power machine (mainly the motor) drives the impeller to rotate in the volute casing, and the air is inhaled from the center of the impeller through the suction port. Due to the dynamic action of the blade on the gas, the pressure and velocity of the gas can be increased. Under the action of centrifugal force, it is thrown to the casing along the blade passage and discharged from the exhaust port. Because the flow of gas in the impeller is mainly in the radial plane, it is also known as radial flow fan.

Centrifugal fan is mainly composed of impeller and casing. The impeller of small fan is directly installed on the motor. Medium and large fans are connected with motor through coupling or pulley. Centrifugal fan is generally single-sided intake, with single-stage impeller; large flow can be bilateral intake, with two back-to-back impeller, also known as double suction centrifugal fan.

Impeller is the main part of fan. Its geometry, size, number of blades and manufacturing precision have great influence on the performance. Only when the impeller is corrected by static balance or dynamic balance can the fan rotate smoothly. According to the different direction of blade outlet, the impeller is divided into forward, radial and backward three types. The top of the blade of the forward impeller inclines to the rotating direction of the impeller; the top of the blade of the radial impeller is radial, which is divided into straight blade type and curve type blade; the top of the blade of the backward impeller inclines to the rotation direction of the impeller.

The pressure produced by the forward impeller is the largest. When the flow rate and speed are fixed, the impeller diameter required is the minimum, but the efficiency is generally low; on the contrary, the pressure generated by the backward impeller is the minimum, and the required impeller diameter is the largest, and the efficiency is generally higher; the radial impeller is between the two. The straight blade is the simplest and the wing blade is the most complex.

In order to make the blade surface have the suitable velocity distribution, the curved blade is generally used, such as the arc blade with equal thickness. The impeller usually has a cover plate to increase the strength of the impeller and reduce the gas leakage between the blade and the casing. The connection between blade and cover plate adopts welding or riveting. The weight of the welding impeller is light and the flow channel is smooth. The impeller of low and medium pressure small centrifugal fan is also made of aluminum alloy.

When the axial-flow fan is working, the power machine drives the impeller to rotate in the cylindrical casing, and the gas enters from the collector. Through the impeller, the energy is obtained, the pressure and speed are increased, and then discharged along the axial direction. Axial flow fans are arranged in three forms: vertical, horizontal and inclined. The diameter of small impeller is only about 100 mm, and that of large fan can reach more than 20 meters.

Small low pressure axial fan is composed of impeller, casing and collector, etc