High View Innovation (hVI)

➥ Structure and Principle:
There are two kinds of aerodynamic noise in Roots blower: rotating noise and vortex noise. The rotating noise of Roots blower is the noise caused by the interaction between the circumferential uneven air flow and the volute when the impeller rotates. The main sound sources are volute, blade and wind tongue. When the impeller rotates, the velocity and pressure of the air flow are not uniform at the outlet of the blade along the circumferential direction. This kind of uneven air flow rushed to the volute before it was flattened, thus forming the pressure pulsation on the volute at any time and becoming a noise source. The stronger the nonuniformity, the greater the noise. The non-uniform exit along the circumference could have been a kind of steady motion, but the existence of the wind tongue has the pressure fluctuation with time, which in turn affects the flow of the impeller, so the air flow on the blade also has the pulsation property with time, so the force on the blade fluctuates with time, making the blade become the second noise source. It, together with the noise source on the wind tongue, is caused by the rotation of the impeller, so it is called rotating noise, also known as discrete frequency noise.

➥ Purpose:
When Roots blower is running, it will produce strong noise. According to the mechanism of noise generation, fan noise includes pneumatic noise, mechanical noise and electromagnetic noise; according to the parts of noise generation, there are intake noise, exhaust noise, casing noise, gear noise (using booster or transmission) and motor or turbine noise, etc.

➥ Features:
● Current difficulties: According to the rotation speed, the main noise spectrum range of roots blower is mostly 50Hz~200 Hz. For these relatively low frequency noises, traditional muffler designs cannot effectively reduce the emission noise of roots blower. As a result, the overall noise reduction of roots blower is very limited, and it is difficult to meet the environmental noise emission standards or the safety and health standards of the labor working environment.
● hVI professional solution：Aiming at the noise emission of Roots blower, developed a new design scheme of Roots blower silencer, which can be equipped with on-site acoustic noise reduction package (sound-absorbing coating) Designed as a Roots blower silencer with wide frequency and high noise reduction, it is very suitable for various operating conditions of Roots blower.

➥ Specifications and Functions:
Customized according to customer needs and noise reduction requirements.

➥ The following is the acoustic simulation result of the insertion loss of the muffler as shown in the figure: