Session: 19-08 Turbine Design

Paper Number: 121990

121990 - Influence of External Heat Transfer on the Thermo-Structural Stress of a Radial Turbine Wheel 

Structural simulations are key for the wheel of a turbocharger’s turbine under extreme exhaust gas temperatures. These simulations enable the assessment of component durability and performance in demanding conditions, facilitate the development of cooling strategies, essential for managing excessive heat, and allow enhancing turbocharger efficiency and preventing catastrophic failures in high-temperature environments. External heat transfer plays a crucial role, since the housing temperature can reach values in the order of 10³ K and the contribution of convective heat to ambient air is one of the major sources of loss.

The present paper aims to assess the influence of natural or forced convection between the turbine’s housing and the external ambient on the temperature and stress distributions of the turbine’s wheel. The methodology adopted for the analysis is based on a two-step approach. First, a three-dimensional steady‑state conjugate heat transfer (CHT) simulation of the entire turbine stage is performed to evaluate the temperature field on the metal body of the turbine. Then, the temperature distribution of the body is imported as a load for the thermo‑structural simulation of the rotor wheel. The numerical setup was validated against experimental measurements of the temperature of the rotor blade. For the evaluation of the structural behavior of the component, the most critical regions in terms of stresses were identified in the backdisc part of the wheel. The results show the variation of the structural response as the external convection is increased from an ideal adiabatic condition to a forced external cooling condition. The impact of the same on the overall performance limits of the turbine are discussed.

Presenting Author: Francesco Balduzzi University of Florence

Presenting Author Biography: Francesco Balduzzi is an Adjunct Assistant Professor at the Department of Industrial Engineering of the University of Florence, where he holds the course on “Operating machines”. He is also a Research Fellow of the International Consortium for Advanced Design and he currently serves as the supervisor of the CFD simulation team within the REASE research group, focusing on applications related to wind turbines, compressors and internal combustion engines.

Authors:

Francesco Balduzzi University of Florence
Pierre-Alain Hoffer Ferrari SpA
Luigi Mosciaro Ferrari SpA
Daniele Mattiello Ferrari SpA
Silvio Rabbolini Ferrari SpA
Nicola Pini Ferrari SpA
Alessandro Bianchini University of Florence
Giovanni Ferrara University of Florence