One of the outstanding issues in turbomachinery aeromechanic analysis is the intra-row interaction effects. The present work is aimed at a systematic examination of rotorstator gap effects on blade aerodynamic damping by using a 3D time-domain single-passage Navier-Stokes solver. The method is based on the upwind finite volume discretization (AUSMD/V) and the single-passage Shape-Correction approach with enhanced accuracy and efficiency for unsteady transonic flows prediction. A significant speed up (by a factor of 20) over to a conventional whole annulus solution has been achieved. A parametric study with different rotor-stator gaps (56%–216% chord) for a 3D transonic compressor stage illustrates that the reflection from an adjacent stator row can change rotor aerodynamic damping by up to 100%. It is shown that this intra-row interference effect on the rotor aero-damping can be qualitatively altered by changing the number of stator blades. Thus, the stator blade count could be considered as a useful aeromechanical control/design parameter. Furthermore, the predicted non-monotonic relationship between the rotor blade aerodynamic damping and the gap distance suggests the existence of an optimum gap regarding rotor flutter stability and/or forced response stress levels.

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