1, the sound absorption
When sound waves incident to the surface, part of the sound energy to be absorbed by the object is converted into other forms of energy, called the sound absorption. Sound absorption performance of materials by absorption coefficient, absorption coefficient is larger, the better sound absorption performance of said materials. The sound absorption performance of materials and materials, structures and the properties of sound waves incident Angle and frequency of sound waves. Sound absorption mechanism of porous sound absorbing material is: material internal inter-permeation of countless small holes, when the sound waves incident to the surface of the material, and the incident to the tiny pores, to cause the air motion inside the pore, close to the wall of hole and air on the surface of the fiber, not easy movement due to friction and viscous resistance, make the sound energy into heat energy and consume. To porous sound-absorbing material, so the good performance of interpenetration between holes and hole, and through the hole to be connected with the outside world, the sound waves can enter inside the material. As corresponding to 1000 Hertz sound wave, 10 cm thick superfine glass wool absorption coefficient is 0.87.
2, the acoustic
Acoustic method is adopted by the noise source closed up, the noise control within a small space, this kind of sound insulation structure called a sound insulation cover. When encountered in acoustic shield, due to the change of the characteristic impedance interface, part of the incident sound can be reflected, part is absorbed, part of the sound energy in the shield continue to spread. The sound insulation performance of the material available through sound coefficient to express. Acoustical transmission coefficient is smaller, says penetrating the sound energy is less, the better materials can sound insulation sex. The sound insulation performance of materials and sound insulation structure, properties and the frequency of the incident sound wave.
3, silencing
Silencing porous sound-absorbing material is fixed on the inner wall of the air flow channel, fixed in the pipeline, or in a certain way to achieve the purpose of weakening the air dynamic noise, decrease the general can reach 10-50 decibels.
Third, reviews, we see not hard, pipe low noise fan basically has the following several reasons:
1, frame, good quality of the motor;
2, the pipe fan blade structure design reasonable science, etc.
3, the use of sound insulation technology processing