Installation effects on fan acoustic and aerodynamic performance

Sound power measurements were performed on an upright vacuum cleaner in order to identify predominant noise generating mechanisms and to recommend corrective noise control modifications that would cause no increase in production costs. These modifications were then implemented and their effectiveness quantified. In general, the noise radiated by the vacuum cleaner is dominated by aerodynamic sources. Aerodynamic interactions occur between the electric motor cooling fan and nearby motor mounting fixtures resulting in intense tones at blade rate and harmonic frequencies. These tones are reduced by as much as 25 dB in level, to the broadband sound power level of the unit, by eliminating certain flow obstructions, and mounting the motor in an alternative fashion. Motor cooling performance is also dramatically improved by the new mounting arrangement resulting in a 26 °C reduction in steady-state operating temperature. © 1999 Institute of Noise Control Engineering. †S0736-2501„99...00101-0‡