Causes of fan surge
The ventilator runs in the system. Due to the different technical performance, the performance parameters need to be adjusted frequently. When the fan's flow rate is continuously reduced to qv, it will cause the airflow to rotate severely in the flow channel. The flow is severely deteriorated. At this time, the air flow that should be continuous flow will be detached in the blade channel, so that the air flow forms an intermittent air mass at the impeller outlet, and the flow at the fan outlet will appear intermittent. Air masses rushed out of the outlet. The ventilator always works in conjunction with the pipe network system. When one air mass flows out of the fan outlet, a negative pressure is generated between the next air mass, and the pressure in the pipe network does not decrease. We all know that the fluid always flows from the high pressure zone to the nip zone. Then, when the airflow flows forward, a negative pressure zone will appear behind it. It will flow until it is equal to the forward pressure and then flow out, and the pressure at the instantaneous impeller outlet will be higher than the negative area at the back. At this time, it will flow backward, and immediately meet the second and second air flow groups, and then start to reverse flow.
Repeatedly, a periodic airflow vibration phenomenon is generated in the entire system. This vibration phenomenon is called spin-off in fluids. It is also called “movement” in turbomachinery. This phenomenon is often called “surge” due to periodic and rhythmic calls in vibration.