Noise characteristics of tunnel fan

Tunnel fan noise is divided into aerodynamic noise, mechanical noise and electromagnetic noise.

Aerodynamic noise can be divided into eddy current noise and rotating noise.Vortex flow noise is the wide frequency band noise generated by the blade rotating in the air, forming the pressure gradient change along the tunnel fan blade thickness direction, causing the vortex flow and airflow turbulence;Rotational noise is the noise that produces periodic pressure on the air, causing the pulse change of air pressure and speed to the surrounding gas.

Mechanical noise is divided into bearing noise and noise stimulated by periodic forces.Bearing noise is caused by the friction and vibration between the relative moving elements in the bearing, and the other is caused by the unparallel or the impact between the relative elements of the rotating part;The noise excited by periodic forces is generated by the eccentric force caused by the absence of parallel static dynamics of the rotating system.

Electromagnetic noise is caused by the subharmonic interaction of the stator and the rotor, so it is called slot noise.Its size depends on the tunnel fan stator, rotor groove cooperation situation.

Aerodynamic noise is the largest, mechanical noise is the second, and electromagnetic noise is the smallest.To control the noise of tunnel fan, first control the aerodynamic noise.