Centrifugal fans are bound to encounter failures after being used for a long time. Strong vibration is one of them. Do you know why centrifugal fans have strong vibration? Let’s listen to what the centrifugal fan manufacturers have to say!

After treatment, the impeller of the high-temperature centrifugal fan has static imbalance. The vibration of the fan shaft is very small, which rules out the possibility that the misalignment between the fan shaft and the motor shaft causes the vibration of the fan casing. The temperature and vibration of the bearings of the high-temperature centrifugal fan are lower than the specified standards, and there is no noise in the bearing box. This also indicates that the probability of vibration caused by poor bearing quality or unqualified installation is low. Even if the fan shaft and bearings vibrate, the vibration of the fan casing will not be very obvious. Since there are no contact points between the shaft and impeller of the high-temperature centrifugal fan and the fan casing, the vibration regularity of the fan casing will not change with the opening degree of the inlet valve.

The distance between the inlet of the high-temperature centrifugal fan and other related parts is less than 5 meters, and it is installed in parallel. The distance from the two outlet air ducts to the main air duct is about 1.5 meters, and there is no smooth transition. This makes the air flow discharge unsmooth. Especially at the inlet of the high-temperature centrifugal fan, it will also encounter the backflow of the air flow from the outlet of the high-temperature centrifugal fan and cannot be discharged in a timely and smooth manner. There is a sense of oppression at the inlet of the high-temperature centrifugal fan. The result of this pressure intensifies the vibration of the casing, making the vibration at the inlet of the high-temperature centrifugal fan significantly higher than that at the outlet.

The fan casing has been fixed on the concrete foundation with 40 bolts to meet the installation standards. The flange connection bolts at the inlet and outlet of the high-temperature centrifugal fan are all equipped with spring washers, and there are no other abnormal phenomena. The inlet and outlet air ducts of the fan are also firmly fixed without obvious instability. It can be said that the rigidity of the fan casing and air ducts is sufficient. If it is not enough, it will cause its resonance frequency to approach the rotation frequency of the impeller, resulting in strong vibration.

The regulation door of the high-temperature centrifugal fan consists of 12 guide vanes. Centrifugal fan manufacturers can use mechanical structures and different connection methods of the guide vanes to make the guide vanes rotate in two directions, clockwise and counterclockwise, so that the incoming air at the inlet of the high-temperature centrifugal fan has a pre-rotation in the clockwise or counterclockwise direction. When the pre-rotation direction of the air at the fan inlet is the same as that of the impeller, the air flow can enter the impeller smoothly and steadily, and the vibration of the fan casing is relatively small.