Understanding the Aerodynamic Damping Behavior of an Axial Compressor Rotor for Industrial Applications

The damping behavior of compressor rotors is a key aspect for an accurate prediction of flutter and forced response vibrations. For the latter phenomenon, it is not rare that at Campbell’s crossings a relevant contribution to the overall damping comes directly from the fluid flow. This topic has been studied from a long time both to design flutter resistant or tolerant configurations, or to provide aerodynamic damping contribution for forced response verifications. Experimental campaigns are usually intended to measure the mechanical damping through in vacuum test campaign, or the overall damping with in-situ measurements (with stream-gages or tip timing techniques), while numerical methods can be applied to provide the aerodynamic damping contribution also considering the impact of multi-row effect. In this context, the paper presents an experimental and numerical investigation of aerodynamic damping of an axial compressor transonic rotor. The effects of multirow interactions are assessed in and out of resonance conditions by comparing single and multi-row CFD analyses with and without vibrating rotor. For a specific responding mode, the numerical predictions are compared with overall damping measured by processing the rotor frequency response showing a satisfactory agreement.