Experimental Investigation of Non-Synchronous Vibration in Axial Compressors

Advances in manufacturing technology allow weight reductions of axial compressors by up to 30%. However, these compressors are susceptible to non-synchronous blade vibrations (NSV), where small blade deflections grow dangerously due to changes in the surrounding aerodynamics. NSV can cause huge programme delays, financial losses and reduced engine efficiency. Despite their growing prevalence, the underlying physical mechanisms of NSV remain poorly understood.
Experimental research on NSV is essential but difficult. To avoid blade failure and damage to experimental rigs, the scope of NSV investigations is limited. Although NSV can be identified in research compressor rigs, the associated fluid mechanics cannot be fully analysed or applied to design.
The PhD proposes a novel experimental approach to investigate NSV. The method involves manufacturing annular patterns of deflected blade geometries undergoing NSV. The motion of the vibrating blades is removed but the instantaneous static position during the vibration is captured. In doing so, detailed experimental campaigns can be carried out to understand changes in the unsteady aerodynamics caused by the deflected blades. This approach allows for safer and more comprehensive research into NSV.