Aeroacoustic characteristics and noise reduction of a centrifugal fan for a vacuum cleaner

Abstract

The aero acoustic characteristics of a centrifugal fan for a vacuum cleaner and its noise reduction method are studied in this paper. The major noise source of a vacuum cleaner is the centrifugal fan. The impeller of the fan rotates at over 30000 rpm, and generates very high-level noise. It was revealed that the dominant noise source is the aerodynamic interaction between the rotating impeller and stationary diffuser. The directivity of acoustic pressure showed that most of the noise propagates backward direction of the fan-motor assembly. In order to reduce the high tonal sound generated from the aerodynamic interaction, unevenly pitched impeller and diffuser, and tapered impeller designs were proposed and experiments were performed. Uneven pitch design of the impeller changes the sound quality while the overall sound power level (SPL) and the performance remains similar. The effect of the tapered design of impeller was evaluated. The trailing edge of the tapered fan is inclined. This reduces the flow interaction between the rotating impeller and the stationary diffuser because of some phase shifts. The static efficiency of the new impeller design is slightly lower than the previous design. However, the overall SPL is reduced by about 4 dB (A) . The SPL of the fundamental blade passing frequency (BPF) is reduced by about 6 dB (A) and the 2 n d BPF is reduced about 20 dB (A). The vacuum cleaner with the tapered impeller design produces lower noise level than the previous one, and the strong tonal sound was dramatically reduced.

Reduction of aero-acoustic noise originating from a high-speed polygon mirror scanner motor in a laser beam printer utilizing air-flow analysis

“…Jeon et al (2003Jeon et al ( , 2004 identified the acoustic characteristics of a centrifugal fan and suggested an impeller design to reduce the tonal noise. They showed experimentally that the overall noise level and the strong tonal noise produced from a vacuum cleaner are reduced by a tapered impeller design.…”

The Overall Perceived Quality Ratings of Vacuum Cleaners in Stationary and Single-working-cycle Conditions

“…Therefore, product manufacturers focused on reducing noise levels produced by the suction units. However, they reached a point where further noise level reduction is hard to achieve or at least not financially feasible [1]. On the other hand, researchers investigated the perceptual aspects of vacuum cleaner sounds and showed that the sound power levels of the products are not sufficient to characterize the users' perception of the product sound (e.g., [2][3][4]).…”

Study on Noise Generation in a High Speed Centrifugal Fan

“…One of the important review is given by Neise which summarized all the efforts to reduce passage tone noise by improving the geometry of the impeller and its cut off [2]. Jeon et al [3] published the method to reduce tonal noise of centrifugal fan by application of tapered impeller and uneven pitched impeller. Yilmaz et al [4] presented the method on numerical noise prediction of a radial fan.…”