Simulation method and dynamic characteristics analysis of complex blade rubbing in aero-engines

This paper focuses on the research of the rubbing simulation method and dynamic characteristics of complex engine blades. Considering the influence of local blade contact and rotor whirl, a three-dimensional rubbing load and blade inertial load model is established through the spatial motion relationship. The above load model is assembled with the reduced-dimensional finite element model of the blade to obtain the rubbing dynamic equation. Combined with numerical solution techniques, a rubbing simulation method for complex engine blades is ultimately proposed. The proposed method is applied to conduct a rubbing analysis of the compressor blades of a certain aeroengine. The results show that tip rubbing can excite two rubbing states, which are related to the rubbing position. During the leading edge of the blade tip rubbing, the intermittent rubbing of the blade is easily to be excited. At this time, the blade repeatedly contacts and separates from the casing, and the blade exhibits high-frequency and high-amplitude modal vibration at 8 000 Hz. During the trailing edge of the blade tip rubbing, the full circumferential rubbing is more likely to be excited, and the blade undergoes static deformation at this time. The non-synchronous whirl of the rotor significantly increases the nonlinearity of the blade rubbing behavior. The vibration frequency of the blade will have complex combined frequencies related to the whirl frequencies f_e and f_n. Reducing the rubbing stiffness and friction coefficient can effectively suppress the overall vibration of the blade under tip rubbing. This paper can provide necessary theoretical method support for the dynamic analysis of aero-engine blades and clearance design.