Effects of multi-source excitations on the dynamic behavior of high-speed rotors in a multi-shaft integrally geared compressor for compressed air energy storage (CAES)

Frequent start-up conditions are a characteristic feature of multi-shaft integrally geared compressors (IGCs) utilized in compressed air energy storage (CAES) systems. These conditions involve multi-source excitations, including mass unbalance, thermal deformation, pressure fluctuation loads, aerodynamic loads, and airflow disturbances, which significantly affect the dynamic behavior of multi-shaft rotors during acceleration and loading processes, thereby impacting the stability of CAES compressors. Initially, a dynamic model for each rotor shaft system was established, taking into account the multi-source excitation loads, and the model's accuracy was verified through experimental tests. Next, the impact of factors such as acceleration time, mass unbalance, and thermal deformation on the critical speeds, nodal displacements, and phase angles of each high-speed rotor during the acceleration process was calculated. Following this, the variation of dynamic characteristics of the rotor due to load changes during the loading process was investigated, and a focused analysis of the nodal displacement response under multi-source excitations, such as aerodynamic loads and airflow disturbances, was performed. Lastly, the computational results were validated against engineering case studies. The findings demonstrate that multi-source excitations have a significant influence on the critical speeds and the time-domain and frequency-domain characteristics of rotor nodal displacements. The computed results, once integrated into the model, are consistent with the engineering case studies and offer insights for the design and operational strategies of CAES multi-shaft IGCs.