Research on mechanical properties of Pelton turbine runner under multi-condition coupling

To investigate the effects of nozzle opening and rotational speed on the fluid-structure interaction characteristics of a Pelton turbine runner, a 1:1 three-dimensional model was established based on the prototype of a Pelton turbine unit from a hydropower station. The stress, deformation, and vibration characteristics of the runner were analyzed through multi-condition simulations. The results show that the jet impact load dominates the amplitude of stress and deformation. An increase in nozzle opening leads to a significant rise in deformation and equivalent stress. Rotational speed nonlinearly influences the structural response through the centrifugal stiffening effect, with stress and deformation being significantly higher under low-speed conditions. The low-order natural frequencies of the runner are higher than the excitation frequencies under runaway conditions, indicating a low risk of resonance but a potential hazard of high-order harmonic resonance. This study can provide a theoretical basis for the structural optimization and safe operation of the Pelton turbine runner.