Study of natural oscillations of a high-power steam turbine near the operating frequency

Abstract

Annotation. Problem. The natural frequencies and features of the natural forms of the turboset-foundation-base system near the operating frequency are considered. Goal. The aim of the work is to study the natural frequencies and modes of natural oscillations of the turboset-foundation-base system near the operating frequency range to assess the vibrational state of the system and determine the causes of increased vibrations. The object of the study is the system of turboset-foundation-base. The system consists of a single reinforced concrete foundation on which a steam turbine and a generator are installed. The subject of the study is the natural frequencies and forms of natural oscillations of the turboset-foundation-base system. Methodology. The study was carried out by oscillation methods and the finite element method. The use of original methods developed directly by the author for constructing models of complex machine-building systems should also be mentioned. Results. As a result of the research, three-dimensional finite element models of low-pressure cylinder bodies, the foundation and the entire turboset-foundation-base system were built. The conducted study allows us to draw a conclusion regarding the causes of an increased level of vibration near the operating frequency and directions for their prevention. Originality. Regarding the methods of constructing a model of the turboset-foundation-base system, their uniqueness should be noted. The features of the applied modeling method make it possible to take into account the variable interaction between low-pressure cylinder bodies and the foundation. Fixpoints are also taken into account. Previous studies of the turboset-foundation-base system did not allow us to determine the nature of the oscillation modes near the operating frequency. Practical value. The results of the work relate to direct practical application. As a result of the work, conclusions were made about ways to increase the vibration reliability of the turbine unit-foundation-base system and further research directions.