An accurate unbalance prediction model for multi-stage disc-separated structure rotor with benchmark transformation

Currently, there is a lack of a multi-stage rotor unbalance prediction model based on actual shafts, and the comprehensive influence of disc and blade errors results in unclear error propagation mechanisms. This prevents the establishment of an effective unbalance prediction model, thus hindering the precise prediction and regulation of unbalance. This paper proposes a multi-stage disc-separated rotor assembly unbalance prediction model based on the common axis of the engine's front and rear shafts. The effects of disk positioning errors and blade assembly errors on unbalance are analyzed. Initially, an unbalance prediction model for a single blade of a single-stage rotor is established. Furthermore, based on the spatial vector summation principle, an unbalance propagation model for a single-stage disc-separated rotor with multiple arrayed blades is developed. Finally, by considering reference transformation and the gradual propagation of errors during the assembly process, a multi-stage disc-separated rotor unbalance propagation model is established, which is subsequently applied to the unbalance prediction and control of multi-stage disc-separated rotor assemblies. Experimental results show that, compared to direct assembly, the best unbalance result of a three-stage rotor after assembly control is improved by 61.8%, thereby achieving the regulation and optimization of unbalance in multi-stage disc-separated rotor assembly. This study proposed a multi-stage disc separation rotor unbalance prediction model including array blade assembly, which can provide guidance for unbalance prediction and assembly optimization in the assembly process of multi-stage disc separation structure rotors of aircraft engines, and has important application value for high-precision rotor unbalance control.