Simulation of Cold Shuts and Misruns in Centrifugal Casting of TiAl Low Pressure Turbine Blades

Abstract

In this work cold shuts and misruns in thin turbine blade test geometries are predicted using a three-phase mold filling and solidification simulation methodology applied to a centrifugal casting process of turbine blades. The methodology is based on a finite-volume method with arbitrary shaped polyhedral control volumes. The Volume-of-Fluid (VOF) approach has been used to capture the phase separation between gas, melt and solid. A High Resolution Interface Capturing (HRIC) scheme has been established to gain sharp interfaces between phases, mandatory for correct calculation of surface tension and wetting angle effects. An additional source term in the momentum equation based on Darcy-law for porous media and Kozeny-Carman relation for the permeability estimation was implemented to model the resistance of the dendrite network to the melt flow. A series of test blades with decreasing thickness has been simulated and cold shuts and misruns predicted at different locations, depending on the blade thickness. Casting trials show an excellent agreement between simulation prediction and experimental findings.