Dynamics Analysis of a Double-Plunger-Type Turbine Overspeed Protection Mechanism

A double-plunger type overspeed protection mechanism has excellent performance in turbine overspeed protection, but the complicated operating principle thereof makes long-term use difficult. In this study, a dynamic model is established to explain the relationship between the motion state and the force situation. Through the analysis of the dynamic model, the specific process of the linked plunger for achieving overspeed protection with tripping action is determined, and the motion law of the inner and outer plungers is clarified. Additionally, the complete solution method and calculation procedure for the tripping speed of the submerged plunger are established, and the specific process for solving the relevant equations with numerical iteration is clarified. Finally, a rigid-flexible coupling virtual prototype model is established, which validates the conclusion that initial eccentric distance and spring stiffness are key factors affecting tripping speed and the motion process of inner and outer plungers.