When the tunnel fan is operating, the tunnel fan blades rotate, the type and amount of air changes, and the speed changes.

We can experiment with two tunnel fans and adjust the rotation speed of the two tunnel fans and the rotation speed of the low pressure tunnel fan and the low pressure tunnel fan. The pressure is mounted on the vent hole and run in the same way to observe the air capacity. The rotation of tunnel fan is not objective, and the main factors affecting the air volume of tunnel fan must be interrelated.

The knowledge and control of these factors are related to the increase in the air flow of tunnel fans. Prerequisite for controlling the air volume of tunnel fan.

Noise reduction method

According to the analysis, the noise source of fan is basically dipole. The total noise level of the tunnel fan is six times its rotation speed. In addition, it can be inferred that the noise is due to the effect of the blades on the air pulse power. The fan can be considered to have two low frequency noise sources, the spiral noise caused by blade moving pressure field and blade pulse dynamic noise. The distance between the static blade and the moving blade of the pneumatic tire is an important factor to produce interference noise.

The blades can also be used as an acoustic barrier to increase the acoustic radiation generated by the lifting pulse at very long distances. The long effect depends on the ratio of the wavelength associated with the lift pulse to the size of the blade used as the lift pulse. The resulting variation in radiation intensity is a large variation in the frequency range greater than 1. Therefore, when the number of upstream and downstream blades of the radiated noise blades is the same and two rows of blades collide with the radiated noise blades at the same time, the effect is greater. The rotor blades can form a sound barrier on both sides of the sound source.

As the static and moving sheet spacing increases, the effect of current interference is much faster than that of tail flow velocity. While the effect of the blade as a sound barrier decreases over time the spacing can be seen to be at least three parameters affecting the interference noise: the waveform of the velocity field the alignment distance of the blade and the small distance of the radiated surface sound of the blade can produce two effects acoustics If the force pulse generated by the stator interference field makes the rotor the sound source, then the stator is the acoustic barrier.