Identification of noise sources in centrifugal blower with acoustic camera

Abstract

A centrifugal blower represents the main noise source in a vacuum cleaner. Noise emitted by the centrifugal blower working as a suction unit has aerodynamic, mechanical, and electromagnetic noise origins. Noise emitted by a suction unit consists of airborne and structure‐borne noise. The contribution of the individual noise source to the total noise level depends on the geometry of the suction unit, rotational speed and on the operating conditions. Operating conditions of a suction unit depend on the amount of dust particles in the dust bag and are constantly changing during operation until a zero flow rate is reached. In order to reduce noise of suction unit at broad range of operating conditions, an identification of noise sources needs to be performed. Identification of most important noise sources on the centrifugal blower was performed with an acoustic camera at the design and off‐design operation conditions. From the analyses we can conclude that the rotational noise usually prevails at the design point of operation, and that the nonrotational noise prevails at off‐design operation. The main source of noise within a suction unit can be attributed to the aerodynamically generated noise, at the design as well as at off‐design operation.