A, fan noise source

Fans are widely used in metallurgy, chemical, petroleum, machinery, cement, construction, and other important department, to promote industrial production, accelerate the pace set set plays a very bad smell positive role. But when the fan operation generated strong noise but serious influence on the quiet environment. It not only can damage people hearing damage, interfere with the workshop nice normal communication links and language of the production safety, talking to bring certain influence; And the rest of the neighbouring residents, organ of the work and school class do have serious interference. Below is a brief introduction to the noise of the fan:

The fan is actually a volumetric compressor, it consists of a pair of vertical meshing waist form each other YeYe round high-speed rotation in conveying gases relative. The machine to turn, the noise of the air dynamic noise is mainly (i.e., air flow noise.) transmission gears noise, motor noise and governing valve until the noise, of which the highest, and the strength of the biggest impact on the air dynamic noise is. It includes the fan when rotating impeller periodically to exhaust air into the cause of the pressure pulsation and produce the periodic exhaust noise, and gas eddy current in the fan in the interface of the impeller splitting the eddy current noise caused by two parts. Among them the strength of the exhaust of the impeller and main speed, exhaust fan of flow and static pressure is related to such factors as the noise spectrum, often with a low frequency noise, and accompanied by some of the peak. And eddy current noise depends on the shape of their impeller relative to the body, air flow velocity and flow pattern, general continuous frequency spectrum of all can produce high frequency noise.

When in certain conditions operation, high strength noise of the fan, respectively from the vent pipe, the cabinet and the place such as the radiation out. In the actual conditions, the fan vent is often and pipelines road connects and closed. Therefore, the intake of radiation noise is the most intense, to the environment and the most serious interference. Measured by that came out of the body, the fan noise, the "A" gear noise level of 105 to 135 decibels or so, and A "C" is for the noise level file of 110 ~ 140 decibel.

Fan noise intensity high not only, and still have complex and continuous frequency components. In order to quantitatively describe its noise in the audio energy within the scope of the distribution, in The Times frequency measurement noise often process according to 63 hz filter to 800 hz eight times frequency band noise frequency process of analysis and test, to get the sound source spectrum characteristic curve, namely the noise level is now process frequency doubled the frequency of relation curves. The noise spectrum curve characteristics are:

First of all, the noise spectrum wider, namely at a wide frequency range are higher noise, and with the low frequency noise as the main component, when static pressure is lower, that is more hours, peak load frequency in low frequency 125 hz or so often; When the boost to the rated static pressure conditions in operation, intermediate frequency 500 hz or so is the emergence of a new noise peak. This shows that work pressure increasing, fan of high frequency noise will have obvious increase.

Fan noise intensity and frequency spectrum characteristics and fan besides work related to the size of the static pressure, but also to the flow rate of the fan speed has the very big relations. As with the increase of flow, noise, and when speed increase accordingly double, fan noise can increase 5 ~ 10 decibel, especially in the increase of high frequency noise more significant.

Second, the fan control measure

Fan noise reduction in addition to consider noise outside, according to the draught, the body of the fan noise and vibration of solid voice sound transmission shall also be attention.

Because of axial flow fans work made a lot of noise, and fan noise also along with the increase of air volume and air pressure and improve. To solve the problems usually fan noise method have the following kinds:

1) the cabinet and the noise of the motor by the sound insulation cover to solve, will be placed in the independent fan fan noise in between, between fan in within the sound absorption, sound insulation treatment.

2) in the fan ventilation system installation outside the muffler attenuation, built-in insert, make noise in through the special structure of the exhaust when cut. Muffler is to reduce air power equipment into, vent radiation or along the tube relay noise of effective measures.

3) the ground layer as far as possible the shutter use silencing shutter.

4) fan hangs the damping spring hanger shock absorber.

According to the source object, noise characteristics, noise reduction requirement, process condition and the installation position factors such as is pertinently designed to ensure that you get good silencing noise reduction effects