Numerical simulation of deformation in large scale hydroturbine blade casting

Abstract

Deformation is one of the most common defects during the casting of large scale hydroturbine blades because of their curved three-dimentional (3D) surface geometry. Inverse deformation is usually applied to the pattern for sand moulds to finally obtain proper shape. However, the value of inverse deformation is hard to be determined. In this paper, a method is presented to determine the inverse deformation values by cycling numerical simulation. The inverse deformation is determined by the criteria of the achievement of even and appropriate machining allowance of the whole casting. This method is applied to a large scale blade casting used in the Three Gorges Power Plant. The calculated inverse deformation is obtained after three cycles. By using the electronic coordinate determination system (ECDS), its surface is measured and the machining allowance values of some points are acquired. The measured and calculated results are in agreement.