Noise reduction and environmental protection of exhaust fan

Noise includes atmosphere dynamic noise, atmosphere dynamic noise, mechanical noise, electromagnetic noise and structural noise.

The dynamic noise of atmosphere is due to the unsteady flow of gas. The noise generated by the mutual infection of gas and gas and gas and objects. From the perspective of noise generation mechanism, it is the disturbance of air flow. It is mainly composed of rotary noise (pressure fluctuation) and eddy noise (turbulence noise). The atmosphere dynamic noise of the exhaust fan is the effect of changing the confusion between noise and vortex noise; The mechanical noise is mainly radiated to the surroundings through the casing of the exhaust fan; The electromagnetic noise of the motor is relatively low compared with the atmospheric dynamic noise and mechanical noise.

A driven fluid machine in which the forward gas is pressurized and vented. It can be made into two types: right rotation and left rotation. The centrifugal exhaust fan relies on the mechanical energy output. The mission rationale is basically the same as that of the turbine shortening machine, but because the gas flow rate is low and the pressure changes little, individuals do not need to consider the change of gas specific volume, that is, treat the gas as an irreversible fluid. The air volume of newly installed small centrifugal exhaust fan will be too large. When the exhaust fan starts to officially operate after being newly installed, or when it is too large or too small during operation, one of the following patterns can be used to eliminate it: change the speed of the exhaust fan to adjust the flow. Control the opening and closing degree of the regulating valve to regulate the flow. Adjust the flow by changing the resistance coefficient of the pipe network. Change the suction fan with higher or lower pressure to regulate the flow.

Changing the noise is when the mission wheel rotates. It is formed by causing the pressure pulsation of gas everywhere. For a particle in a given space, the blade on the wheel strikes the gas medium around. When the blade passes through, the pressure of attacking this particle gas will rapidly fluctuate once, changing the blade to continuously sweep one by one, which will constantly produce pressure pulsation, causing great non-uniformity of air flow, thus radiating noise everywhere.