Most of the production industries are inseparable from the use of fans. Centrifugal fans can not only be used as ventilation equipment, but also as blowers for boilers and induced draft fans for dust removal equipment, but most of them are designed with volutes. , instead of the box-type, no volute design, what is the role of the volute of the centrifugal fan? What effect does the volute tongue on the volute have on the fan?
1. The role of centrifugal fan volute
The volute of the centrifugal fan is commonly known as the casing, which is shaped like a snail, hence the name volute. The section of the volute has two types: square and round. Generally, the medium and low pressure fans are square, and the high pressure fan is round. The volute can be regarded as a channel of airflow, which can collect and guide the gas leaving the impeller, gradually reduce the speed of the airflow, and make a part of the kinetic energy become static pressure, so the flow channel gradually expands along the periphery of the impeller, namely:
1. Collect the gas thrown out from the impeller and guide it to the outlet of the fan;
2. Convert part of the dynamic pressure (kinetic energy) of the airflow at the outlet of the impeller into static pressure.
If the volute of the centrifugal fan is removed, the static pressure head of most of the air volume range will be significantly reduced, and the efficiency of the fan in the high-pressure area will also be reduced.
The air velocity at the outlet of the volute is generally very large. In order to effectively utilize this part of the energy, a diffuser can be installed at the outlet of the volute to reduce the flow rate. Because the airflow deflects toward the impeller when it flows out of the volute, the diffuser is generally made to expand toward the side of the impeller, and its diffusion angle θ is usually 6 to 8 degrees.
2. The influence of the volute tongue on the volute on the fan
The extension of the spiral of the volute to the outlet section is called the volute tongue (wind tongue), and its purpose is to prevent part of the airflow from circulating in the volute. The geometry of the volute tongue and its distance from the outer circle of the impeller have a certain influence on the efficiency and noise of the centrifugal fan:
1. The volute tongue can prevent the gas from circulating in the volute.
2. The gap between the upper surface of the volute tongue and the outer diameter of the impeller has a great influence on the noise. If the gap is small, the noise will be large; on the contrary, if the gap is large, the noise will be reduced.
3. The arc on the volute tongue has no great influence on the aerodynamic performance of the fan, but has a greater impact on the noise. If the radius of the arc is small, the noise will be relatively large.
Regarding the function of the volute of the centrifugal fan, the above is all the content introduced by the centrifugal fan manufacturer. I hope it can be helpful to everyone.