Geometric Decomposition and Structural Shape Modification for Turbomachinery Blades

Abstract

<p>An efficient and precise method is presented for the generation of turbomachinery blade models in nominal configuration, i.e., the "cold-shape" given the blade geometry at operating conditions, i.e., the "hot-shape." The shape correction technique has two main components: a preprocessor that generates a plate finite element model of the hot-shape geometry, and postprocessor decomposes the hot-shape blade surface model into a mean camber surface and an associated set of thickness functions. A plate finite element mesh is generated on the resulting mean camber surface. The finite element model is used as input for specialized analysis software for cold-shape correction which provides displacements due to unloading the blade. The postprocessor constructs the nominal cold-shape blade model in two steps. First, the nodal deflections are applied to the hot-shape finite element model to generate a cold-shape mean camber surface. Then the original hot-shape thickness functions are applied to the cold-shape mean camber surface to generate characteristic blade section curves which are lofted to define the cold-shape blade model. Several examples of turbomachinery blades in their hot-shape and resulting geometry are presented to demonstrate the capabilities of the technique.</p>