A centrifugal compressor is a type of turbomachine that increases the pressure of a fluid by converting kinetic energy coming from a rotating component into potential energy. A centrifugal compressor stage consists of an impeller, which is the rotating component that transfers energy to the working fluid, and a diffuser, which converts the kinetic energy to potential energy, thereby increasing the static pressure.

To maximize the efficiency of centrifugal compressors, impeller rotational speeds have increased over the years, resulting in more demanding structural limits. In particular, fluid-structure interactions (FSI) are becoming critical from the preliminary design phases, requiring researchers to develop models that can quickly and accurately assess the aeromechanical integrity of the impeller, especially in terms of forced response.

In this presentation, a brief overview of the standard numerical approaches for forced response and flutter calculations on centrifugal compressor impellers will be given. After that, new models, both analytical and numerical, are proposed to quickly assess the aeromechanical risk of the impeller, with special emphasis on the impeller side cavities located between the impeller and the stationary components. These models are based on the propagation of acoustic waves in a compressible flow and were conceived to avoid solving the full set of Navier-Stokes equations to evaluate the forcing functions that excite the impeller. All the models were applied to a centrifugal compressor test case and the results obtained were compared with the benchmark solutions, showing a very good agreement. Although additional test cases should be considered to better assess the reliability of the models, they prove to be a very interesting tool for fast aeromechanical analysis.