Principle of diesel engine muffler
Porous acoustic materials are used to reduce noise.A resistive silencer is a material that is fixed to the inner wall of the air passage or arranged in a certain way in the pipe.When the sound wave enters the resistive muffler, part of the sound energy is converted into heat energy by friction in the pores of the porous material and dissipates, which weakens the sound wave passing through the muffler.Resistive silencers are like pure electrical resistance circuits, and sound absorbing materials are similar to resistors.Therefore, people call this kind of silencer resistive silencer.The resistive muffler is bad for middle and high frequency muffler and bad for low frequency muffler.
Does the diesel engine muffler work
According to its working principle, muffler can be divided into resistance muffler, resistance muffler and impedance compound muffler.Impedance muffler is mainly used to reduce noise, sound-absorbing material sound-absorbing material is fixed in the airflow circulation pipe wall or in a certain way is arranged in the pipeline, when sound waves enter the muffler, most of the sound energy is absorbed, silencing effect, resistance muffler has the advantage of high frequency in the wide range silencing, especially for high frequency sound waves have prominent silencing effect.The disadvantage is that the service life is short in the high temperature water vapor and the gas which has the erosion effect to the sound absorbing material.Usually used for home, office air-conditioning;Large wind tunnel, jet engine test shop, etc.The resistant muffler is also called acoustic filter, which is divided into resonance type, expansion chamber type and interference type and so on.The simplest expansion chamber type is a thick tube with a large section on the air passage tube, but its end is a thin tube. The section length of expansion chamber (large tube) can be adjusted to change the reflection and interference performance of sound waves, so as to change the noise attenuation and the maximum noise attenuation frequency.It is different from the resistive muffler in that there is no sound absorbing material. The resistive muffler has the advantages of simple structure, high temperature resistance and gas erosion resistance, and good low frequency noise elimination performance.The disadvantage is that the muffler frequency band is narrow, which is mainly used in the inlet and outlet of automobile engine and other piston engines.Impedance composite muffler is made by combining the first two advantages.There are not only resistive sound absorbing materials, but also resistive filter elements such as resonance cavity and expansion chamber inside the filter, so it has a good acoustic attenuation effect in a wide frequency range.
