Modeling and analysis of own oscillations of the TFB with turbine 500 Mw

Проведен анализ собственных колебаний системы турбоагрегат-фундамент-основание с турбиной мощностью 500 МВт в частотном диапазоне приближенном к частоте колебаний электромагнитной природы от генератора. Объектом исследования является система турбоагрегат-фундамент-основание.. Для исследования выбрана система с паровой турбиной, которая содержит несколько типовых корпусов. Для моделирования и проведения численных расчетных исследований использован метод конечных элементов. Построены геометрические и конечно-элементные модели системы турбоагрегат-фундамент-основание с учетом особенностей взаимодействия гибких корпусов турбины с фундаментом. Проведены расчеты собственных колебаний. Получены собственные частоты и формы колебаний. Полученные результаты дают качественную оценку причин повышенной вибрации отдельных элементов рассматриваемой системы.The analysis of the own oscillations of the turbounit-foundation-base system is carried out. The system includes a reinforced concrete foundation, a 500 MW turbine with five bodies, a generator and four condensers. To study the chosensystem with a steam turbine, which contains several typical buildings. The relevance of the study is due to the presence of turbounit-foundation-base systems with a long operating time and a significant development of the base resource of increased levels of vibration. On the other hand, the relevance and novelty of the results is due to the lack of previousresearch on the given object and subject of research. A system with a steam turbine with four typical identical flexible housings and one rigid body of high weight is considered. The system of turbine-base-base in the frequency range close to the frequency of oscillations of electromagnetic naturefrom the generator was considered. The object of the study is a turbo-base-base system. The method of finite elements is used for modeling and conducting numerical calculations. The geometric and finite-element models of the turbo unit-foundation-base system are constructed taking into account the features of the interaction of flexible bodies of the turbine with the foundation. The modeling of the foundation is done using a system of core and mass finite element. The rigid body of the steam turbine and the generator were modeled using a system of massive finite elements. The most flexible bodies of the steam turbine weremodeled using a shell, coreand mass finite element system. The basis was modeled using the system of stiffness and boundary conditions. Capacitors were modeled using a system of stiffness and boundary conditions. The peculiarity of the calculation models is the detailed three-dimensional modeling of flexible bodies of the steam turbine. The applied simulation technique is unique and allows us to carry out a detailed analysis of the system's own oscillations. The calculations of proper oscillations have been carried out. Own frequencies and forms of oscillations are obtained.The obtained results give a qualitative estimation of the internal oscillations of separate elements of the considered system of the turbo-aggregate-foundation-base and the system as a whole. The results ofthe calculations were used inthe study of the causes of increased vibration of the turbo unit-foundation-base system and its individual elements

Effect of tungsten on the temper brittleness in steels with 9%

The impact toughness and the structure of high-chromium martensitic steels with different tungsten contents are studied after tempering at 300 – 800°C. It is shown that when the tungsten content is increased from 2 to 3%, the temperature range of the irreversible temper embrittlement is widened and the impact toughness is decreased by a factor of

Unusual behavior of the Portevin - Le Chatelier effect in an AlMg alloy containing precipitates

Stress serration patterns and kinematics of deformation bands associated with the Portevin - Le Chatelier effect in an Al-Mg alloy were investigated by analyzing the evolution of the applied stress and axial strain distribution. In contrast to usually observed strain localization behaviors, referring to propagating and static deformation bands at high and low strain rates, respectively, the propagation mode was found to persist in a wide strain-rate rang

Effect of tantalum on the tensile properties of 12%Cr martensitic steels for steam blades

Co-modified 12%Cr martensitic steels are perspective materials for steam blades for fossil power plants which are able to work at ultra-supercritical parameters of steam (T=620-650°C, P=2530 MPa

Effect of deformation temperature on formation of ultrafine-grained structure in the age-hardenable Cu-Cr-Zr alloy

The effect of the temperature of plastic deformation performed by equal channel angular pressing on the structure and physical and mechanical properties of the age-hardenable Cu-Cr-Zr alloy has been studied. Plastic deformation results in the formation of an ultrafine-grained structure in some regions with an average grain size smaller than 1 μm, a supersaturated solid solution decomposition, and the precipitation of disperse particle

Effect of thermomechanical treatment on the microstructure and mechanical properties of a low-carbon low-alloy steel

The effect of thermomechanical treatment on the microstructure, tensile strength and impact toughness of low-carbon low-alloy steel is considered. The developed microstructure is characterized by grain elongation along the rolling direction. Both the yield strength and the ultimate tensile strength increase with a decrease in test temperature. The ultimate strength at room temperature is 797 MPa, and at 77 K the ultimate strength increases to 1198 MPa. The steel samples subjected to tempforming exhibit impact toughness of KCV = 410 J/cm2 at room temperatur

The role of deformation in coagulation of M₂₃C₆ carbide particles in 9% CR steel

The kinetics of the growth of M₂₃C₆ carbide particles in 9% Cr steel of the martensitic class with a high content of boron is studied under conditions of prolonged aging and creep. It is shown that the grainboundary diffusion is a mechanism that controls the coagulation of these carbides in the case of annealing. Deformation accelerates the enlargement of particles during creep, which is explained by additional diffusion along dislocation line