Усовершенствование конечно-элементных моделей лопаточных конструкций

Abstract

Изложена методика построения конечно-элементной модели лопаточных конструкций, имеющих широкое распространение в энерг омашиностроении. С использованием трехмерных криволинейных конечных элементов решена задача определения собственных частот колебаний лопаток турбины. Получена лучшая сходимость численного решения по сравнению с использованием моделей на основе распространенных типов конечных элементов. Также результаты численного решения хорошо согласуются с экспериментальными данными.The problem of turbine engines blades finite elements models development has been studied. All calculations have been provided for the turbine blades constructions that are widely spread in the power-plant engineering. The matter is that turbine blades have constructional non-homogeneity, which hardly ever could be correctly explained, using well-known finite elements and their mathematical dependences. On the other hand, the mathematical model should be as simple as possible for the purpose of its wide usage in the process of blades design. That is why the new finite elements model, which consists of three-dimensional curvilinear isoparametric finite elements, has been developed. It has been used for the free oscillation frequencies calculation. The whole model can be divided into three sections according to the three types of elements, used for the blade’s feather and two types of its conversion description. Such approach gives an opportunity to describe the whole blade as the superposition of the developed sections and make the process of turbine blades free oscillation frequencies spectrum calculation more correct and even compact. It has already been found that the convergence of turbine blades free oscillation frequencies calculations is much faster. The comparison was provided between the mathematical model, developed on the base of upper mentioned finite elements and the models, based on the two widespread types of elements such as “tetrahedron” and “prismatic”. It is also should be known that the results of the turbine blades frequencies calculation are close to the experimental data when the developed finite elements are used. The developed three-dimensional finite elements of curvilinear type and the mathematical model, based on them could be used for the turbine and compressor blades stress-strained problem solution.