A bladed rotor, such as a rotor of a gas turbine engine, includes a central hub, one or more discs and a plurality of blades secured to respective discs and projecting outward from the hub. The bladed rotor having multiple rotor blades rotates about a longitudinal central axis. Because of non-uniform distribution of mass within the rotor assembly and the blades, it is difficult to achieve a perfect balance for a bladed rotor. However, minimizing imbalances within a rotor assembly is essential for minimizing vibration and noise and maximizing the efficiency and performance of the rotor (and turbine engine).
Currently, rotor assemblies are balanced by separately balancing each disc or component and aligning respective individual rotor discs or components in the assembly so that the high point of one disc is offset by the low point of its adjacent disc. The blades are distributed by mass about the theoretical geometric centerline of each disc. The main drawback of this approach is that it is a trial-and-error method which does not guarantee the optimal alignment of the rotor assembly because the separate centerline of each disc or component is not aligned with the centerline of the rotor assembly. For example, alignment of two rotor discs' centerlines may satisfactorily align those two discs, but introducing a third disc's high point or low point in the assembly may be impractical to align with the other two centerlines. The blades may then be redistributed about each disc in an arbitrary, trial-and-error manner in the hope of achieving some acceptable balance. A static balance machine may be used to add weights to the disc or blades to help in achieving a rudimentary balance. Consistency and repeatability is missing in this trial-and-error procedure.