How to control the noise of axial flow fan!

Noise control of axial flow fan is also a technology! How to control the noise of axial flow fan well! The following technology introduces how to control the noise of axial flow fan!

Superposition of blade passing frequency and broadband aerodynamic noise components. The blade passing frequency is determined by the following formula: the frequency spectrum of fan noise is a composite spectrum.

Fn=Nbn/60 Hz

Where:

B ---- Number of blades

N ---- Fan revolution, rpm

N ---- Harmonic number: n=1 (fundamental frequency), n=2 (second harmonic)

It is not only related to the structural form of the fan, but also the sound level of fan noise. It is also related to its working state (determined by total pressure and air volume). Different series and models of fans have different sound levels. Under different working conditions, their sound levels are also different. When fans work at the highest efficiency point, their sound levels are often taken as low values.

The concept of Level A has arisen. The specific A sound level refers to the A sound level generated by the ventilator under unit flow (1 m/min) and unit total pressure (1 mm water column). The specific A sound level of the unified fan under different working conditions is the highest efficiency, in order to better characterize the noise function of the fan. It is lower than A sound level measurement. The specific A sound level of different series of fans under rated working condition indicates the noise level and product quality of this series of fans. Therefore, at present, the noise level ratio A is widely used as the limit indicator of fan noise at home and abroad. The sound level ratio A of fans of different models in the unified series is basically similar. The higher the processing accuracy of the fan, the better the pneumatic actuator can be, and the lower the sound level than A is.

Forward facing blade centrifugal fan, generally speaking. Its specific sound level A is lower than 2dBA backward plate blade centrifugal fan, 30dBA wing blade centrifugal fan, 25dBA shaft smooth fan, and 38bBA. Under different working conditions, the sound level of fan noise is determined by the following formula:

LA=LSA+10LgQP dBA

Where:

La ---- A sound level at the fan inlet (or outlet), dBA;

Lsa ---- specific A sound level of fan inlet (or outlet), dBA;

Q ---- Air volume, m3/min;

P --- Fan total pressure, mm water column

Muffler and sound insulation box can be used. The common method to control fan noise is to install resistive muffler at the inlet and outlet of the fan. For occasions with higher noise reduction requirements. The shock absorber shall be installed between the unit and the foundation. The above methods can generally achieve significant noise reduction effect.

It can provide noise elimination devices, noise elimination boxes and shock absorbers for various fans. There are many noise control equipment factories in China for the noise problem of fans. Technically, China has basically been able to effectively control, and low-noise fans have begun to emerge.

Therefore, in conclusion, it is very easy to eliminate the noise of axial flow fan in the future!