Numerical investigations of the structural behavior of dynamically highly loaded fans with special consideration of mistuning

In industrial fans, damage can occur even before the nominal service life is reached, the causes of which have not yet been satisfactorily clarified. This is the motivation for the present AiF project, in which it is being investigated whether the impeller, i.e. the most heavily loaded component in the machine, can be excited to damage-relevant vibrations by the unsteady flow. The collaboration with the Institute for Thermal Fluid Machinery and Machine Laboratory at the University of Stuttgart and the German Aerospace Center in Göttingen is intended to clarify in particular whether production-related tolerances can lead to additional aerodynamic excitation of the impeller (so-called "mistuning"). A further aim is to formulate design recommendations that take into account the dynamics and modal properties of the structure, which is subject to manufacturing tolerances and therefore detuned. In addition, it will be investigated whether mathematical models based on the "harmonic balance" method are suitable for reflecting the essential characteristics of the flow during mistuning. For this purpose, valid reference solutions based on the time-dependent RANS equations with high-quality turbulence models must first be generated.