2D finite-element modeling of 3D blade structures with axisymmetric and non-axisymmetric shapes

Abstract

Prediction of the clearance between the components of a rotor and casing of a gas turbine is generally based on the two-dimensional (2D) finite-element analysis of the overall layout, the three-dimensional (3D) finite-element analysis of the local parts, and the deformation of the gas turbine components caused by other, unimportant 3D effects, such as cold-build clearances and ovalization. Using this, the variation of clearance, the minimum clearance, and the contact evaluation between the components with respect to the operation time are evaluated. Detailed 3D modeling of the overall shape for transient thermal-structural analysis for the prediction of clearances between components under the operating conditions of gas turbines with complex components, including both axisymmetric and non-axisymmetric shapes, is not economical in terms of computational time and cost. To address this problem, it is efficient to perform finite-element analysis by means of 2D modeling based on the crosssectional information of the gas turbine components. At this moment, the 2D finite-element modeling for the axisymmetric and non-axisymmetric structures of the gas turbine is important for predicting the correct and accurate deformation. In this paper, we show that 2D modeling can obtain results similar to those of 3D finite-element analysis for the original shape. The proposed 2D finite-element modeling method for rotor and support of a gas turbine that includes both axisymmetric and non-axisymmetric shapes will enable rapid and effective prediction of the components' behavior.