Numerical and experimental anaylsis of the thermo-mechanical load on turbine wheels of turbochargers

CID, FEA, and experimental testing have been combined in order to investigate the lifetime limiting design deficiencies of a turbine wheel in a turbo charger. Thermocouples have been applied to the same radial turbine wheel to provide boundary conditions and validation data for the simulations. The tests have been performed on a turbocharger gas-stand. Based on two steady state CHT-calculations for two distinctly different operating points the heating process of the wheel has been simulated in a transient temperature calculation. Since the resulting temperature gradients induce thermal stresses, the temperature distribution serves as a boundary condition for the subsequent structural analysis. To obtain realistic stress distributions, centrifugal forces also need to be accounted for. In this way, the influence of the thermal stress on the overall stress can be evaluated.