Comprehensive Control Of Vibration And Noise Of SSR-type Roots Blowers

Vibration and noise of Roots blowers is an important issue which influences the use and promotion of products, so it is of great significance to control the vibration and noise of machines and equipments. In this paper, a SSR-200 Roots blowers is selected to investigate the generating mechanism of vibration and noise and its controlling methods. The following tasks have been performed in this paper.The vibration and noise generation mechanism of Roots blowers was analyzed and it is found that blowers'vibration is mainly casued by four aspects:(1) The vibration caused by imbalance; (2) Vibration caused by the rotating stall and surge; (3) Blades wear, medium adhesion, causing random changes in the rotor imbalance; (4) Possible electromagnetic vibration. The Roots blower noise is mainly aerodynamic noise (according to different working conditions and intake noise, exhaust noise, radiation and radiation-dominated, respectively) and the mechanical noise component.Blower oblique isolation system dynamics model established on a flexible and limited panel is built and the power flow expression with compound excitation system is derived, then we have some numerical simulations with MATLAB. The results showed that the thicker the base plate, the smaller vibration energy will be passed to the basement, so in isolation of the blower thicker and hard foundation should be used, and when the height of the plate is 0.2m, it will not only raise the isolation effect, but also save the stuff; On the other hand, the variation of the angle of the isolator will affect the degree of isolation effect, as it can not only avoid the resonance point but also minimize the transmission of vibration energy, then the isolators'best installating angel should be between 30°and 60°.The SSR roots blower's noise generated from the pneumatic pulse are analyzed, and compared the noise level between two-leaf and three-leaf clover impeller, the results show that the aerodynamic noise is the main source of noise of Roots blower, compared with two-leaf impeller Trefoil impeller's pneumatic pulse is smaller, the load changement is small, and mechanical strength is higher.The structure of the Roots blower was improved as follows:the two-leaf impeller is replaced by three-leaf impeller, the outlet is changed into spiral-shaped and the structure for gas-return is designed. The results show that the blower noise has been decreased greatly, SSR-200 Roots blower's noise is in lower than 100dB (A).In the last part of the paper, the acoustic cover of the Roots blower was designed by appropriate choice of absorption material, reasonable design and muffler sound absorption board structure and the pipe, with the use of acoustic cover the noise value of the blower is lower than 10-15 dB (A).The method and practice of vibration and noise control of RSS Roots blowers give a good example and an introduction for similar machines's vibraton and noise control.