SENSITIVITY ANALYSIS FOR TURBINE BLADE COMPONENTS

A practical Jacobian derivative based methodology is developed for determining sensitivities applicable to the mechanical design of turbine blade components. A domain parameterization approach is adopted to determine semi-analytic sensitivities of isotropic eight-noded (hexahedron) isoparametric finite elements with respect to geometric shape design variables. Shape design variables considered are dovetail skew angle and dovetail offset. General sensitivity equations are derived for the structural responses of displacement, strain, and stress. The present study adopts a parametric solid model of the component and employs an automated hexahedron finite element meshing utility. This enables an integrated seamless solid model (geometry) to finite element (meshed solid) generation whereby the geometric shape design variables are modified. The developed design sensitivities are demonstrated on a generic turbine blade configuration that has multiple cavities and turnarounds. Derived sensitivity information provides useful design guidelines for initial preliminary product design as well as key components that can be adopted for a design optimization procedure.