A general model for passive balancing of supercritical shafts with experimental validation of friction and collision effects

Passive balancing devices for rotary systems consist of masses that are free to move in concentric guides about a shaft axis. At supercritical speeds, the balancing masses automatically assume positions that counter any imbalance due to uneven mass distribution in the system. A comprehensive physics-based non-linear model of a rotary system with passive balancing was formulated including balancing mass collision and friction. An experiment was conducted to quantify the performance and dynamic behavior of a single-plane passive balancing device and to compare experimental results to model predictions. A parametric study validated the proposed modeling of the balancing mass interaction with other balancing masses and with the balancer track. In this research, the passive balancing device on average reduced shaft transverse vibrations experimentally by 62 percent at steady state. Models available in the literature predicted vibration amplitudes to within 68 percent of the experimental values. The presented model, accounting for balancer track friction and balancing mass collision, improved the accuracy of predicting shaft vibration amplitudes by a factor of 3.9 when compared to published models (18 percent vs. 68 percent).