Sound Quality for Micro Axial Fan with Blade Run-Out

Abstract

This paper describes sound quality changes caused by a sound aerodynamic failure in a micro-axial fan when applying acoustic diagnostic methods at a cooling fan motor assembly line. The aerodynamic failure sound was focused to a rotational fan blade tone and a blade passing noise with a change in the fan blade run-out. Experimentally obtained results clarified the correlation between the sound quality metrics (Sharpness, Roughness, Fluctuation strength, Tone-to-noise ratio) and the blade run-out. Furthermore, an acoustic diagnosis technique for fan blade run-out is proposed using an adaptive spectrum enhancer. This proposed acoustic diagnosis technique is used for an adaptive feedback algorithm using an internal model control architecture to extract an abnormal periodic signal including aerodynamic sound generated by a rotating micro-axial fan. The experimentally obtained results show that the blade passing sound signal with the blade run-out change was improved by about 10 dB using this adaptive feedback algorithm.