Model reduction and damping mistuning identification method for mistuned rotating bladed disks under variable speed

Abstract

The bladed disk is a critical component of aircraft engines, typically operating under high rotational speeds, significant aerodynamic loads, and variable-speed conditions. Modeling and parameter identification of rotating bladed disks are more challenging than their stationary counterparts. This work introduces an enhanced reduced order model (EROM) tailored for rotating bladed disks, particularly under variable-speed conditions. The EROM accounts not only for stiffness mistuning but also for blade-to-blade damping variations. By using finite element solutions of the tuned bladed disk and cantilevered blade at only three rotational speeds, the EROM can accurately predict the free and forced responses across a wide speed range. In addition, the EROM-based damping mistuning identification method (EROM-DMID) is proposed. A key innovation of this approach is that blade-to-blade damping variations can be identified at any speeds using only speed-independent physical mistuning parameters, which can be obtained in advance through modal testing. A detailed numerical case study is provided to validate the proposed EROM and EROM-DMID methods. Compared with full finite element models (FEM), the EROM demonstrates high accuracy in predicting both the free and forced responses of mistuned bladed disks at any rotational speeds. Finally, the EROM-DMID method was validated using FEM-generated modal test and vibration test surrogate data. Results show that the damping identification error remains below 3 % even at speeds as high as 17500 rpm. The proposed approach offers significant potential for online parameter identification and model updating of mistuned rotating bladed disks.