Yashchenko A. Improvement of Vibrational Reliability of NPP Centrifugal Pumps Based on Generation of Reliable Mathematical Models of Dynamic System Rotor – Pump Casing

In the dissertation, the scientific and practical tasks of ensuring the vibration stability of the NPP centrifugal pump units have been solved. This task is based on the creation of a reliable mathematic model of the centrifugal pump unit dynamic system as a whole. The dynamic subsystem of the pump rotor has been analyzed, it has been established that natural frequencies of vibration of the pump unit largely depend on bearing housing compliance. As the rotor is an integral part of the pump unit, the dynamic characteristics of the pump unit have been analyzed. Results obtained during calculations and experimental determination of natural frequencies of the pump unit have shown that natural frequencies of the subsystem are differ from the natural frequencies of a system to a large extend, it means that the analysis of the system as a whole allows performing the reliable determination of dynamic qualities of the pump unit. The technique of development of the pump unit mathematic model has been created. It has been investigated the effect of the flexibility of pump fasteners on the pump dynamic characteristics. The system of the vertical pump unit has been analyzed and it has been established the significant difference on natural frequencies of isolated subsystem and natural frequencies of the system as a whole. Basic design approaches for detuning the pump unit from resonant modes of operation have been created.