Efficient and silent cooling of electric drives - basics, measurement techniques and computational approaches

This paper will provide an overview of different mechanisms of sound generation and present important measurement and computational techniques for the determination of the flow and acoustic field in electric drive systems. Two basic phenomena of sound generation can be distinguished: flow-induced sound created by unsteady flow fields, and vibrational sound due to moving surfaces. Besides these basic mechanisms, complex interactions of both are possible. A complementary methodology is introduced, which enables a higher aerodynamic efficiency of the cooling system to be achieved in conjunction with noise reducing measures. This work focuses on modified aerodynamic inflow conditions to the impeller of the cooling unit, which may increase the energy conversion efficiency as well as lower the noise emission of the system.