Experimental investigation of non-synchronous vibration and its mechanism analysis by using a cantilever beam-like compressor cascade

With the increasement of unsteady load and the extensive utilization of light-weight material, compressor blade is encountering increasingly serious flow induced vibration problems. Among which, non-synchronous vibration (NSV) has received special attention due to its complex generation mechanism and significant impact on high cycle fatigue. To better understand the physical mechanism causing NSV in compressor, this study designed a cantilever beam-like compressor cascade and made a detailed investigation about its flow separation induced vibration by means of experimental and numerical methods. The experiments were conducted at 9 engine representative conditions and the data of both on-blade pressure and structural response were measured simultaneously. Results show that, the effect of Ma number on the dynamic response will increase with the increasement of incidence angle and there is a strong nonlinearity. The effect of incidence angle on the dynamic response shows obvious bifurcation phenomenon. The results of large eddy simulation (LES) further reveal that the obvious characteristics of the dynamic response are caused by the laminar separation bubble (LSB) of suction surface, and the periodic separation and reattachment of boundary layer provides initial excitation sources for NSV. The unsteady excitation acts on blades in the form of energy and then forces the blades to vibrate with low order modes. The vibration amplitudes are closely related to the separation points and increase as the separation points move forward.