Analysis of dynamic characteristics of variable intake turbine rotor based on fluid-solid coupling

Abstract

To address the issue of vibration exceedance in a variable intake turbine rotor system, the optimized system undergoes dry and wet modal analysis as well as harmonic response analysis, examining the impact of key parameters and opening variations on its dynamic characteristics. The results show that: The critical speed of the rotor system is elevated to 60,434 r/min, representing a 20% increase over the design speed. No resonance is observed, and the amplitude of the unbalance response diminishes from 1.05 mm to 0.13 mm. The most sensitive locations for unbalance in the first three orders of steady state are identified at the impeller disk and the magnets. The critical speed of the rotor system rises with increased bearing stiffness, stabilizing once the stiffness surpasses 10⁹ N/m. Additionally, the imbalance measure alone influences the response amplitude, maintaining a proportional relationship. As the variable inlet turbine’s inlet angle expands, the first-order critical speed of the rotor system under fluid-solid coupling conditions diminishes, while the overall magnitude of the imbalance reaction escalates. This study’s conclusions can enhance the stability of power cycle operations associated with the variable inlet turbine and serve as a reference for the optimum design of the rotor system.