Noise reduction of dry vacuum pump using the boundary element method to model impeller blade passage frequency

Acoustic field analysis was conducted to propose noise reduction measures for the suction housing of a vacuum pump used in dentistry. The target frequency for reduction was selected by measuring the sound pressure level during steady-state operation, allowing identification of the primary noise sources through intensity and vibration measurements. The impeller area was analyzed by designing a full-scale analytic model for sound field analysis using reverse engineering, including precise 3D modeling. The inner boundaries were then separately extracted to complete a model for acoustic analysis. The characteristics of the inner suction housing area were analyzed using the Boundary Element Method (BEM). Noise reduction measures were proposed by analyzing the characteristics of the suction housing with respect to the differences in excitation frequency brought about by changing the number of impeller blades used. The acoustic frequency response function (FRF) of the inner suction housing was obtained by applying BEM. The relationships between the suction housing and the noise source were investigated to propose noise reduction measures. The proposed measure of reducing impeller blade number was validated by showing that it would avoid resonance in the suction housing by moving the BPF to a lower frequency. Thus, this study proposed the reduction of the number of impeller blades to reduce the noise of the current suction housing design considerably while maintaining its performance.