New Design of Fan Hood Reducing Device.mini fan heater Manufacturing

　　Environmental protection centrifugal fan is a very common fan in modern times. It is widely used because of energy saving. The noise emitted by the environmental protection centrifugal fan is a problem, and the noise will cause health damage to the staff in the factory, so the environmental protection centrifugal fan needs noise reduction. Here we will learn about some noise reduction solutions of the Taiwanese fan brand's environmentally friendly centrifugal fans.

　　  1. Install a muffler on the inlet and outlet pipes of the environmental protection centrifugal fan

　　  In the noise of environmental protection centrifugal fans, the aerodynamic noise radiated from the inlet and outlet is the largest, so this local noise should be reduced first. The installation of mufflers at the inlet and outlet of the environmental protection centrifugal fan is the most effective measure to suppress the noise of the fan. At present, there are many varieties of mufflers, mainly based on resistance and resistance. The ventilator generally uses resistive mufflers. The general resistive mufflers include tubular, honeycomb, chip and folded plate mufflers.

　　  2. Inclined volute and tongue, increasing volute-lingual gap and volute-lingual radius

　　The cyclic pulsating aerodynamic force generated by the air flow of the impeller cascade of the environmental protection centrifugal fan causes the interaction of the volute tongue to generate rotational noise. The magnitude of this noise is related to the violent level of the pulsating aerodynamic force and the headwind area of the volute tongue. You can try to make the volute tongue into an inclined type. , the pulsating aerodynamic action area of the same phase is small, and the radiated noise is also small. The rotating airflow with uneven speed and pressure distribution behind the blade cascade will generate noise when interacting with the volute tongue. The closer the interval is, the louder the noise. Usually, a larger radius of the front end of the wind tongue can reduce the rotational noise and eddy current of the centrifugal fan. noise without affecting the aerodynamic performance of the centrifuge.

　　  3. Environmentally friendly centrifugal fan adopts rotary diffuser

　　  The space formed by the diameter of the wheel cover and the wheel disc is larger than the diameter of the outlet is a rotary diffuser. In a normal radial or forward impeller, on the one hand, the absolute velocity of the airflow at the outlet of the blade is relatively high, and when it flows into the volute, it suddenly expands, producing intense vortex noise. On the other hand, the de-flow area near the outlet of the blade duct periodically impacts the surrounding gas, increasing the rotational noise. Under this condition, the rotary diffuser is used to reduce the outlet speed of the impeller, which alleviates the influence of the above two aspects and reduces the noise. Regarding the backward impeller, the noise reduction effect of the rotary diffuser is not obvious. At the same time, it must be noted that if a diffuser is used, the optimal radial clearance and vane installation angle should be reasonably selected, otherwise large discrete noise will be generated.

　　  4. The air inlet of the environmental protection centrifugal fan is provided with a rectifier ring and a baffle

　　  Because the size of the air outlet of the impeller blade of the centrifugal fan is usually larger than the size of the air inlet at the front disc, when the airflow moves in the fan, many eddy currents will be generated in the arc section of the air inlet.

　　   constitutes aerodynamic noise. A rectifier ring and a baffle can be added at the outer periphery of the fan volute at the fan inlet, which can effectively prevent the airflow from forming eddy currents at the fan inlet, thereby reducing

　　  The aerodynamic noise produced by the environmental protection centrifugal fan.

　　  5. Other noise reduction methods

　　  In addition to the above aspects, there are other noise reduction methods, such as the use of inclined blades for the impeller, the use of unequally spaced blades, the slots on the blades or the installation of separation sheets between the blades.

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