Silencer ((Muffler)) is a device to stop the sound propagation Changsha takchitinited Electromechanical Technology Co Ltd design and production and allow air to flow through, is an important measure to eliminate air dynamic noise. Muffler (patent number: ZL201420804814.6) is installed in the air power equipment (such as blower, air compressor, boiler exhaust, generators, pumps and other exhaust mouth noise larger equipment) on the air channel or the inlet and exhaust system noise reduction device. There are many kinds of mufflers, but the noise mechanism of the muffler is different. Senior expert He Jie divides them into six main types, namely, resistance silencer, resistance muffler, impedance composite muffler, micro perforated plate muffler, small hole muffler and active muffler.
Damping silencer
It mainly uses porous sound absorption material to reduce noise. The sound absorbing material is fixed on the inner wall of the air flow channel or arranged in a certain way in the pipeline, and the resistance silencer is formed. When the acoustic wave enters the resistive muffler, a part of the sound energy is rubbed into the pores of the porous material and converted into thermal energy dissipation to weaken the acoustic wave passing through the muffler. Resistive silencers are like electrical pure resistance circuits, and sound absorbing materials are similar to resistors. Therefore, people call this muffler as a resistive muffler. The resistance muffler has good effect on middle and high frequency noise elimination and low frequency noise elimination effect. (mainly used for generator silencers)
Resistant silencer consists of a tube and a combination of the sharp interface, seemed to be an acoustic filter and similar electrical filter, each with a tube or chamber is a mesh filter, inductance and resistance of pipe in air quality equivalent to the electrical, called the sound quality and resistance. The volume of the air in the chamber is equivalent to the electrical capacitance, which is called acoustic smoothing. Similar to the electrical filter, each chamber with a tube has its own natural frequency. When contains various frequency components of the sound waves into the first tube, only certain frequency sound waves can in the vicinity of the first mesh frequencies through the mesh to a short second mouth, and other sonic frequencies are not through the mesh. Only in the chamber to back reflection, therefore, we call this filter structure the function of acoustic acoustic filter. By choosing proper tube and chamber combination, the noise of some frequency components can be filtered out so as to achieve the purpose of noise elimination. The resistance muffler is suitable for the elimination of medium and low frequency noise. Combining the resistive structure and the resistant structure in a certain way, an impedance composite muffler is formed. Micro perforated plate muffler
In general, pure metal sheet is used to drill holes with a hole diameter less than 1mm on the sheet, and the perforation rate is 1% 3%. By choosing different perforation rates and different cavity depths, the spectral performance of the silencer can be controlled so as to achieve a good sound rejection effect in the required frequency range. The structure of the small hole silencer is a straight tube with a closed end, and there are many holes drilled on the wall. The principle of hole muffler is based on the spectrum of jet noise as the basis, if the total area remained unchanged and with many small jet nozzle to replace, when the air flow through the spectrumwill holes jet noise when moved to HF or UHF, the audible components decrease the spectrum, thereby reducing the interference and hurt.
The basic principle of active muffler is that in the original sound field, an acoustic wave which is equal to the original sound pressure size and is opposite to the original sound pressure is generated by the electronic equipment, so that the sound field is eliminated in a certain range with the original sound field. The muffler is a set of instruments, mainly composed of microphones, amplifiers, phase shifting devices, power amplifiers and loudspeakers. The new type of high efficiency spray resistant series silencer can be widely used in power generation, chemical industry, metallurgy, textile and other industrial factories and mines, for various types of boilers, turbine exhaust, fan, safety door and other equipment silencing sound down. The series silencer is developed according to the principle of resistance, spray and resistance compound silencing. It has many advantages, such as large noise, small volume, light weight, convenient installation and no maintenance. Silencer frequency characteristics of silencers. The effect of anti - jet silencer on frequency noise is superior. The suitable wind speed of muffler is 6-8m/s, the highest should not exceed 12m/s, and attention should be paid to the pressure loss of muffler. Attention should be paid to the net cross section area of the muffler, and when the air duct and the muffler are connected, it is necessary to enlarge the treatment when necessary (when the wind speed is limited).
Installation of silencers such as silencers shall have independent load-bearing booms or bases, and shall be connected to the sound source equipment by means of a flexible joint. When the two silencing elbows are connected in series, the connection space between the two elbows should be 2.5 times longer than the diagonal length of the elbow section. For the environment system with high temperature, high humidity, oil mist and water vapor, microporous structure silencing equipment is usually used. For the clean environment such as operation room, recording room, clean workshop and other environmental systems, microporous structure silencing equipment should be adopted. When the adjacent houses are connected with each other, attention is paid to the influence of the indoor noise through the pipeline, and the air outlet is used as a silencer when necessary