Introduction to different types of mufflers
1. Resistive muffler
The resistive muffler uses the sound-absorbing material or sound-absorbing structure arranged on the inner wall of the tube, and relies on the pores of the sound-absorbing material to cause the sound wave to cause air and material vibration in it to generate friction and viscous resistance, and convert sound energy into heat energy. Absorption, so that the noise propagating along the pipeline attenuates quickly. The resistive muffler has a better muffling effect on medium and high-frequency noise. The factors that affect the performance of the resistive muffler are: the type of sound-absorbing material, the thickness and density of the sound-absorbing layer, the shape and size of the air flow channel, the air velocity and the length of the muffler . The sound absorption performance of a sound-absorbing material is expressed by the sound absorption coefficient α, which is the ratio of the sound energy absorbed by the material to the incident sound energy. The larger the sound absorption coefficient, the better the sound absorption performance. Resistive mufflers include tube type, slice type, format, folded plate type, acoustic flow type, small chamber type and elbow.
2. Resistant muffler
The resistant muffler is formed by connecting the air pipe and the small chamber, and uses the sudden change of the inner cross section of the pipe to reflect the sound wave propagating along the pipe back to the sound source, and play a sound attenuation effect. Resistant muffler has good low and medium frequency noise elimination performance, and does not need to be lined with porous sound-absorbing materials, so it can be used in high temperature, high humidity or corrosive gas occasions. However, the muffling frequency range is narrow, the air resistance is large, and it takes up a lot of space.
3. Resonance muffler
The pipe opening is connected with the resonance cavity, and the air column at the neck of the hole of the perforated plate and the air in the cavity form a resonance sound absorption structure. This muffler has strong frequency selectivity and is generally used to eliminate low-frequency noise.