Understanding the Acoustic Behavior of Electrical Drives

1. The first type of noise excitation originates from time varying forces acting on solids. These forces provoke mechanic vibrations (structure bound sound) within the solid parts which propagate until the outer surface of the bodies. At this outer boundary the vibrations are partly transferred to the adjacent fluid as a result of a fluid-structure-interaction (FSI). 2. The second type of noise excitation provokes fluid bound vibrations directly. This can be observed in fans, ventilation exhaustions and fast moving parts. Here the vibrations are generated due to the turbulent flow of the fluid directly.