1. Noise characteristics at low speed
When the Ventilation Fan is running at low speed, its noise level is relatively low. At this stage, the motor rotates slowly and the mechanical vibration generated is relatively small. Due to the low speed, the frequency of the blade cutting the air is also low, and the air flow is relatively smooth. The noise generated at this time mainly comes from the slight electromagnetic vibration inside the motor, the weak friction of the bearing, and the slight friction between the air and the blade and the housing. This noise may appear as a continuous, slight hum in a quiet environment, usually around 30-40 decibels, similar to the slight background noise in a quiet library environment. Moreover, due to the low speed, the frequency of the noise is also relatively low, and the human ear is relatively less sensitive to this low-frequency noise, so when running at low speed, the noise of the Ventilation Fan is often not easy to attract people's attention.
2. Changes in noise during medium speed operation
As the speed of the Ventilation Fan increases to medium speed, the noise level begins to gradually rise. As the motor speed increases, the mechanical vibration intensifies, and the friction sound of the bearing and the electromagnetic vibration sound inside the motor increase. At the same time, the frequency of the blade cutting the air increases, and the speed and turbulence of the air flow increase, which makes the friction and collision between the air and the blade and the shell more frequent. The noise at this time will become more obvious, which may reach about 40-50 decibels, similar to the sound level of normal indoor conversation. The noise during medium-speed operation contains more frequency components, including low-frequency motor vibration noise and medium-high frequency noise generated by air flow, and the timbre of the overall noise will become more complex.
3. Noise conditions during high-speed operation
When the Ventilation Fan reaches high-speed operation, the noise level increases significantly. The high-speed rotating motor produces strong mechanical vibrations, which not only come from the rotating parts inside the motor, but also include the resonance of the entire Ventilation Fan structure caused by high-speed operation. The blades cut the air at a very high frequency, making the air flow very turbulent and generating strong aerodynamic noise. The noise at this time may reach 50-60 decibels or even higher, similar to the noisy ambient noise in an ordinary office. The noise during high-speed operation is mainly high-frequency noise, which is harsh and easy to cause discomfort to people, and because of the high noise intensity, it will be very obvious in a quieter environment.
4. Overall law of noise changes at different speeds
In general, the noise level of the Ventilation Fan increases with the increase of speed, and the frequency components of the noise gradually change from low frequency to more high frequency components. This change law is determined by the mechanical characteristics of the motor, the interaction between the blades and the air, and the structural characteristics of the entire Ventilation Fan. When designing and using the Ventilation Fan, understanding this law helps to choose the appropriate speed to balance the ventilation demand and noise control, and also provides a theoretical basis for further reducing noise, such as by optimizing the motor and blade design, using shock absorption and sound absorbing materials and other measures to reduce the increase in noise levels at different speeds.
