12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The accurate prediction of the life cycle in turbomachinery design is one of the most challenging issues. Traditionally, life cycle calculations for radial turbine wheels of turbochargers focus on mechanical loads such as centrifugal and vibrational forces. Due to steadily increasing exhaust gas temperatures of automotive and commercial engines in the last years, thermo-mechanical fatigue in the turbine wheel is a major topic of current investigations. In order to account for the thermally induced stresses in the turbine wheel and the turbine housing as a part of the standard design process, a fast method is required for predicting metal temperatures. In the present paper, a fast method to calculate the transient temperatures in a radial turbine is presented. In this method the specific heat capacity of the solid state is reduced by a speed up factor in order to shorten the duration of a transient heating or cooling process. With the shortened processes, the computing times can be reduced significantly. After the calculations, the resulting times are transferred into realistic heating or cooling times by multiplying them with the speed up factor. The method is evaluated against experimental data and against the results of a numerical method known from literature. The method shows a good agreement with those data.