Aerodynamic noise due to complex internal flow through cordless vacuum cleaner and suction tower station

Abstract

Although the demands and sales of cordless vacuum cleaner are on the rise in the global home appliance markets, consumers face the inconvenience of short battery life and frequent emptying of the dust box. To solve this inconvenience, a station tower that can automatically charge the battery and empty the dust box has been developed. However, aerodynamic noise generated when the station tower sucks dust causes another inconvenience. The purpose of this study is to identify the major aerodynamic noise sources that occur when such a station tower is connected to a wireless vacuum cleaner and operate, and to develop a low-noise design based on this. First, the entire flow path of a cordless vacuum cleaner and a station tower was simulated using the unsteady compressible RANS equations. Then, the main aerodynamic noise sources were identified using the vortex sound sources. From these results, the flow region through the head throat of the cordless vacuum cleaner was identified one of the most significant aerodynamic noise sources. Based on the identified noise source mechanism, new throat design was proposed, and its validity was investigated using a high-resolution Large Eddy Simulation technique. It was found that the strength of vortex sound source of pipe flow through the new head throat was much less than the original one. Finally, the new design geometry was applied to create a prototype, and the sound pressure spectrum measured for the prototype was compared to the original, which showed that the radiated noise level of the new one was less than the original one.