The method of noise reduction of high temperature fan

1. A turbulent fluidization device is added at the inlet (outlet) of the impeller
Adding a turbulent device (metal mesh) at the inlet or outlet of the impeller blade of a high-temperature fan can immediately convert the laminar flow boundary layer on the back of the blade into a turbulent flow boundary layer, delaying the separation of the boundary layer on the back of the blade, or even not separating , the trailing edge of the blade is installed with a net, and the airflow velocity and pressure gradient behind the net can quickly become uniform. If the net is in the vortex area, the vortex area can be greatly reduced, which can further reduce noise.
2. Reasonable cochlear tongue gap and cochlear tongue radius
When the airflow and the blades are in relative motion, the velocity and pressure in the airflow wake at the trailing edge of the blades are smaller than the mainstream area, so that the airflow velocity and pressure distribution behind the cascade are uneven. This uneven airflow is rotating, due to the dynamic If there is a volute tongue at the airflow outlet of the leaf, the interaction between the unstable flow and the volute tongue will produce noise, and the closer the distance is to the noise, the stronger the noise will be. Usually, a larger radius of the front end of the wind tongue can reduce the rotation noise and noise of the high-temperature fan. Vortex noise.
3. Inclined tongue
The periodic pulsating aerodynamic force generated by the periodic pulsating velocity of the airflow of the blade cascade of the high-temperature fan also causes the interaction of the volute tongue to generate rotational noise. If it is inclined, the area of action of the pulsating aerodynamic force of the same phase is small, and the radiated noise is also reduced.
4. Enhance the aerodynamic load of the cascade and reduce the peripheral speed
Strong forward blades are used for high-temperature fans, and the multi-blade impeller is beneficial to increase the aerodynamic load of the cascade. Under the same air volume and pressure, the peripheral speed on the outer circle of the impeller blades can significantly reduce the noise of the high-temperature fan.
5. Set up a zigzag structure on the air inlet and outlet sides of the moving blade
The zigzag structure on the inlet and outlet air sides of the moving blade can make the laminar flow boundary layer on the blade change into turbulent flow earlier, so as to avoid the unstable wave in the laminar flow boundary layer from causing the vortex separation, so that the vortex separation will reduce the noise. reduce.
6. Set up an acoustic resonator at the cochlear tongue
An acoustic resonator is set at the cochlear tongue. When the sound wave reaches the resonator, the gas in the small hole and the cavity moves back and forth under the action of the sound wave. The moving gas has a certain quality, and it resists the movement caused by the action of the sound wave. , At the same time, when the sound wave enters the aperture of the small hole, due to the friction and damping of the neck wall, a considerable part of the sound energy is lost due to heat loss. In addition, the gas-filled cavity has the property of hindering the pressure change from the small hole. Due to the combination of these factors, when the gas passes through the resonator, the noise is reduced.