The Harm Of Axial Flow Fan Stalling

1. Stall can lead to damage to the fan, indicating that axial flow fans typically exhibit rotational stall after stalling. Due to rotational stall, the blades of the fan are subjected to periodic forces. If the fan operates in the stall zone for a considerable period of time (or a short period of time when the stall frequency is equivalent to the blade natural vibration frequency), it will cause blade fracture and damage the other mechanical components of the impeller.
2. Stall may lead to surge if the volume and resistance of the pipeline system are appropriate. When the stall pressure of the fan decreases, the pressure in the outlet pipeline will be higher than the pressure generated by the fan, causing the airflow to reverse. At the same time, the pressure in the pipeline will rapidly decrease, and the fan will deliver gas to the pipeline. However, due to low flow rate, the fan will stall and the airflow will reverse. This phenomenon occurs in cycles, known as surging. With the occurrence of surge, the fan current also fluctuates significantly and the noise is astonishing. The destructive effect of fan surge is significant, and it can damage the fan in a short period of time. It is necessary to immediately stop the fan operation.
It can be seen that stall and surge are two different concepts. Stall is a necessary condition for surging, but not a sufficient condition.
3. Stalling may cause parallel running fans to compete with each other, posing a threat to the safe operation of the generator set. After one of the two parallel operating fans stalls, there may be a phenomenon of "competing for wind" between the two fans and they cannot operate in parallel; Although the two typhoons can operate in parallel, the total output of the two typhoons may not reach the required value, affecting their load-bearing capacity.