A Balancing Method for Multi-Disc Flexible Rotors without Trial Weights

Rotor dynamic balancing is a classical problem. Traditional balancing methods such as the influence coefficient method and the modal balancing method, have low balancing efficiency because they need to run many times to add trial weights. Although the model-based balancing method improves the balancing efficiency, it cannot accurately identify the position, amplitude and phase of each unbalance fault for rotors with multi-disc structures, so it is difficult to apply it to actual balancing. To solve the above problems, based on the traditional modal balancing theory, this paper deduces that the continuous and isolated unbalance in the rotor-bearing system can be represented by isolated unbalance on several balancing planes approximately. The model-based method is used to identify the above-mentioned equivalent isolated unbalances, and then the corrected mass is added to the balancing planes so as to complete the balance of multiple flexible rotor without trial weights. Considering the practical situation, the proposed balancing method includes two steps: low-speed balancing and high-speed balancing. The proposed balancing method is verified using three and four-disc rotors. The simulation results show that the balancing method can effectively reduce the vibration of the flexible rotor after low-speed and high-speed balancing, and the amplitude at the measurement point is reduced by 79.74~97.60%, respectively.