A centrifugal fan is a machine that relies on the input of mechanical energy to increase the pressure of the gas and exhaust the gas. The centrifugal fan is also a driven fluid machine. Centrifugal fans are widely used in ventilation, dust extraction and cooling of factories, mines, tunnels, vehicles and buildings; ventilation and induction of boilers and industrial furnaces; and cooling and ventilation in indoor air-conditioning equipment and household appliances; grain Drying and delivery. The working principle of a centrifugal fan is to use gas as an incompressible fluid with a low speed. The turbo compressor is basically the same, but because the gas flow rate is low and the pressure does not change much, it is generally not necessary to consider the change of the specific volume of the gas, that is, to treat the gas as incompressible Compressed fluid processing.
The classification of centrifugal fans can be divided into centrifugal, axial flow, diagonal flow and cross flow types according to the direction of gas flow. Fans are divided into axial flow fans, centrifugal fans and diagonal flow (mixed flow) fans according to the flow direction of the airflow after entering the impeller. Fans are divided into press-in local fans (hereinafter referred to as press-in fans) and explosion-proof electric motors placed outside or in the flow channel, and explosion-proof electric motors are located in the explosion-proof sealed cavity withdrawable local fans. Performance parameters of centrifugal fans The performance parameters of centrifugal fans mainly include flow, pressure, power, efficiency and speed. In addition, the size of noise and vibration is also the main fan design index. The flow is also called the air volume, which is expressed by the volume of gas flowing through the fan per unit time; the pressure of the centrifugal fan is also called the wind pressure, which refers to the increase in the pressure of the gas in the fan. There are static pressure, dynamic pressure and full pressure; power refers to the input power of the fan, that is, the shaft power. The ratio of effective fan power to shaft power is called efficiency.
The centrifugal fan is essentially a variable flow constant pressure device. When the speed is constant, the theoretical pressure-flow curve of the centrifugal fan should be a straight line. Due to internal losses, the actual characteristic curve is curved. The pressure generated in centrifugal fans is greatly affected by changes in intake air temperature or density. For a given intake volume, the lowest pressure is generated at the highest intake temperature (lowest air density). For a given pressure and flow characteristic curve, there is a power and flow characteristic curve. When the blower is running at a constant speed, for a given flow, the required power increases as the intake air temperature decreases. Many people in the industry have a stance on the development of the domestic fan industry. In fact, from the domestic situation, the development space of domestic fans is still very optimistic, and it will not be as stagnant as some people think. From the perspective of development, the use of fans is constantly increasing, which means that fans are still very popular, especially the use of centrifugal fans is increasing. Of course, fans are facing a severe development situation. Evidence-based, though, but the opportunities and challenges facing the wind turbine industry depend on how you view it.
The domestic centrifugal fans are relatively backward in design theory and design methods. Many product developments use imitation and analog methods. There is a serious lack of theoretical basis and experimental research data. Processing equipment and technology levels are also relatively backward. Low efficiency, low degree of product serialization and generalization, few specifications and varieties, and pump efficiency, quality and reliability, sealing performance, corrosion resistance and other aspects are still far from foreign products. With the continuous development of science and technology, people have higher and higher requirements for the use of fans. As far as the current development trend of foreign fan technology, it will follow the direction of increasing fan capacity, high efficiency, high speed miniaturization and low noise. development of.
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