Blower is a kind of equipment that easily produces noise pollution and has a wide range of uses. On the other hand, it is also more difficult to control blower noise. Among them, blower surge is a relatively common type of noise pollution, and it is also a very difficult problem to control. Blower surge is mainly caused by excessive temperature, excessive air humidity, or excessive load, etc. It is very difficult to solve. Let us take a look at the blower noise control methods to prevent surge.
There are two methods to prevent surge, manual and automatic, both of which are to install a bypass pipe at the outlet of the fan. When starting the fan, it should be turned on first, and then gradually turned off when the start-up is completed. When signs of surge occur, the automatic air release valve will automatically open to release air according to the preset program, causing the fan inlet flow to increase, and the fan operating point can be moved from the surge zone to the stable zone. This gradually increases the outlet pressure and gradually sends the compressed air into the pipe network. Under the condition that the outlet pressure is greater than the pipe network pressure, the bleed valve gradually closes or stays in a suitable position. Manually operated valves must be operated by workers familiar with the details following the procedures for automatic valves.
Determining whether the fan has entered surge conditions cannot be accurately calculated theoretically. It is generally judged based on experience and observed fan operating phenomena. The first is to observe the airflow noise in the fan outlet duct. When approaching surge conditions, the noise emitted from the outlet pipe alternates between high and low, causing periodic changes. When entering surge conditions, the noise immediately increases sharply, and even popping sounds appear. The second is to observe the vibration of the fan body. Entering the surge zone, the machine body and bearings will vibrate strongly. The third is to observe the changes in fan outlet pressure and inlet flow. During normal operation, the outlet pressure and inlet flow rate do not change much, but when entering the surge zone, both change greatly.
