Influence of Pre-Swirl, Rotor Speed and Blade Count on Aeroelastic Coupling Mechanisms During Stall Inception of a Transonic Compressor

Abstract

Abstract The aeroelastic effects during stall inception in modern axial compressors have been a research focus for decades and yet are not fully understood. Experimental investigations, conducted at the 1.5-stage transonic compressor test rig at TU Darmstadt, using extensive unsteady aerodynamic and structural instrumentation, show global trends and influencing parameters on non-synchronous vibration and associated unsteady aerodynamics. During stall inception, aerodynamic disturbances occur and vary in count, size, cell speed and trajectory. The interaction with non-synchronous blade vibration results in changing stability mechanisms, indicating influences of pre-swirl, rotor speed and blade count on the traveling aerodynamic wave as well as the coupling with the structural wave. Supplementary numerical simulations of the test setup extend the available set of aerodynamic and aeromechanical data, and support the experimental findings. The study reveals the convective nature of NSV, influenced by the propagation speed of aerodynamic pre-stall disturbances, depending on rotor speed and pre-swirl, as well as its interaction with blade vibration, based on specific phase synchronization conditions and rotor blade count.