Analysis of the noise source of the cooling fan

Many suppliers have purchased a cooling fan and found that there will be some noise after using it for a period of time, and they will feel that it is broken and where the noise comes from. Today, Tongchi will popularize it for everyone. u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e The main sources of noise from cooling fans are as follows: u003cbru003e u003cbru003e u003cbru003e 1. Fan vibration u003cbru003e u003cbru003e u003cbru003e If the physical center of mass of the fan rotor and the center of inertia of the rotating shaft are not on the same axis when the fan rotor rotates, the rotor will be unbalanced. The closest distance between the physical center of mass of the rotor and the center of inertia of the shaft is called the eccentricity. The imbalance of the rotor causes the eccentricity. When the rotor rotates, a force is generated on the shaft support due to the centrifugal force to form vibration, and the vibration is transmitted to the shaft through the base path. Parts of machinery. u003cbru003e u003cbru003e u003cbru003e 2. Fan wind noise u003cbru003e u003cbru003e u003cbru003e When the fan is working, the blades periodically bear the pulsating force of the uneven air flow at the outlet, which produces noise; on the other hand, due to the uneven distribution of the pressure on the blade itself and the blades, the disturbance of the surrounding air and parts during rotation It also constitutes rotating noise; in addition, the turbulent attachment layer, vortex and vortex separation are generated when the gas flows through the blade, which causes the pulsation of the pressure distribution on the blade and generates vortex noise. The noise caused by these three reasons can be comprehensively referred to as 'cutting wind noise.' Generally, fans with large air volume and pressure will have relatively large cutting wind noise. u003cbru003e u003cbru003e u003cbru003e 3. Fan noise u003cbru003e u003cbru003e u003cbru003e Wind noise sounds only the wind noise, but the abnormal sound is different. When the fan is running, if there are other sounds besides the wind sound, it can be judged that the fan has abnormal noise. Abnormal noise may be caused by foreign matter or deformation in the bearing, collision due to improper assembly, or uneven winding of the motor winding, causing looseness, which may cause abnormal noise. u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e The noise of the fan is mainly caused by the above points, so it is normal for the fan to have noise during a period of use. Each fan has a noise value. As long as it is within this range, it will not affect the normal use of the fan. The principle of whether your DC cooling fan or AC cooling fan is the same, you can use it with confidence.