APPLICATION OF THE METHOD OF INITIAL PARAMETERS TO ANALYSIS OF COUPLED HYDROMECHANICAL VIBRATIONS IN PIPING SYSTEMS. PART 3. ANALYSIS OF FORCED VIBRATIONS IN STEAM PIPING OF WWER-1000 POWER UNIT

摘要

The paper addresses forced vibrations in piping subsystems, which are induced due to the formationand separation of turbulent vortices in the flow of a fluid being transported. The excitationfrequency is not a constant number but can take on values from a certain range, thus leading todifficulties and ambiguities in the vibration analysis of piping. To solve this problem, a so-calledenergy approach is put forward which enables one to determine the most physically governedfrequencies of forced vibrations. The approach essentially consists in searching for the naturalfrequencies and modes of the fluid hydrodynamic vibrations whereby the minimum amount ofenergy leaves the piping subsystem, while the maximum one remains inside. The validity of theproposed approach is verified by test examples. The proposed methods have been used to analyzepiping forced vibrations induced by turbulent vortices in the steam flow in the secondary coolantpiping of nuclear power plants with WWER-1000 reactor. Natural frequencies and modes ofmechanical, hydrodynamic, and coupled hydrodynamic vibrations have been determined; somerecommendations of how to minimize the level of vibrations have been worked out.