Моделирование и анализ собственных колебаний корпусных элементов турбоагрегата мощностью 500 МВт

Abstract

Проведено моделирование системы турбоагрегат-фундамент-основание с турбиной мощностью 500 МВт. Объектом исследования являются наиболее гибкие элементы системы - корпуса цилиндров низкого давления. В исследовании рассматривается паровая турбина, которая содержит четыре типовых корпуса. Для моделирования и проведения численных расчетных исследований использован метод конечных элементов. Построены геометрические и конечно-элементные модели элементов системы турбоагрегат-фундамент-основание и всей системы в целом. Проведены расчеты собственных колебаний. Получены значения собственных частот и собственные формы колебаний. Полученные результаты позволяют дать качественную оценку вибрационного состояния системы турбоагрегат-фундамент-основание и выявить причины повышенной вибрации отдельных ее элементов.

The modeling of the turbo unit-foundation-base system with turbine with a capacity of 500 MW is carried out. The object of research is the most flexible elements of the system - the body of low pressure cylinders. Determining the spectrum of vibrations of body elements of turbine units is a complex task. In most cases, the spectrum of vibrations is determined experimentally. As a rule, the spectrum of vibrations of body elements is determined for a set of measures to eliminate the increased level of vibration. That is, attention to the phenomenon of resonance is often applied after almost repeated fixation of the presence of increased vibration. These facts include increased noise, the presence of clearly deformed body elements, emergency stops of the power unit. Mathematical modeling of the spectrum of vibrations of body elements of a turbine unit is a complex task. On the one hand, the complexity of the task is due to the large volume of work of three-dimensional modeling of units of the power unit to create a reliable model with more degrees of will. On the other hand, the complexity of the problem is related to the peculiarities of taking into account the nonlinear characteristics of the elements of the turbo unit-foundation-base system and the connections between the complex elements of the system. However, in order to prevent and eliminate emergencies associated with vibrational reliability, it is necessary to conduct calculations based on spatial models of the power unit with a sufficient number of degrees of freedom. The study examines a steam turbine containing four typical enclosures. For the simulation and conduct of numerical computational studies, the method of finite elements is used. The geometric and finite-element model elements of the turbo-base-base system and the whole system as a whole are constructed. Calculations of own oscillations are carried out. The eigenfrequencies and their own oscillations are obtained. The obtained results allow us to give a qualitative estimate of the vibration state of the turbo unit-foundation-base system and to identify the causes of increased vibration of its individual elements.