TY - THES

T1 - Dynamics of heat transfer in turbochargers

AU - Schäfer, Karl-Heinz

N1 - embargoed until 03-02-2018

PY - 2016

Y1 - 2016

N2 - The objective of this master thesis is the complete flow and thermal analysis of a comprehensive assembly and the derivation of a simulation methodology for numerical analysis. The object of investigation is the turbocharger S410 Euro4 of the automotive supplier BorgWarner Turbo Systems. State-of-the-art is the separated analysis of fluid and solid domains or a coupled simulation in different simulation tools. In contrast to this workflow the investigated flow domains as well as the considered solid domains are modeled by CFD methods with the simulation tool AVL FIRE. The entire multi-domain calculation grid is discretized by a unstructured mesh of polyhedrons excepting both impeller flow domains which are modeled by a block-structured mesh. Moreover, the rotational speed in the flow domains is modeled by a Moving Reference Frame. All domains are set up as stand-alone calculation cases which are interacting with the ACCI coupling module of FIRE. The simulated load case is defined at the operating point with the highest turbine and compressor efficiency according to the measured turbocharger performance maps. In conclusion, in comparison to measurements the simulation methodology provides reliable results and gives additional insights to the fluid-solid interactions and their governing heat transfer processes. Furthermore, the polyhedral calculation grid is beneficial to the convergence behavior and heat transfer assessment. The obtained results indicate further research potential with respect to transient turbocharger calculations and the consideration of the lubrication system for a validation of the heat transfer to the engine oil. Finally, it can be stated that the provided simulation approach has large potential for the dimensioning of the complex assemblies and will continue to grow in importance in the coming years.

AB - The objective of this master thesis is the complete flow and thermal analysis of a comprehensive assembly and the derivation of a simulation methodology for numerical analysis. The object of investigation is the turbocharger S410 Euro4 of the automotive supplier BorgWarner Turbo Systems. State-of-the-art is the separated analysis of fluid and solid domains or a coupled simulation in different simulation tools. In contrast to this workflow the investigated flow domains as well as the considered solid domains are modeled by CFD methods with the simulation tool AVL FIRE. The entire multi-domain calculation grid is discretized by a unstructured mesh of polyhedrons excepting both impeller flow domains which are modeled by a block-structured mesh. Moreover, the rotational speed in the flow domains is modeled by a Moving Reference Frame. All domains are set up as stand-alone calculation cases which are interacting with the ACCI coupling module of FIRE. The simulated load case is defined at the operating point with the highest turbine and compressor efficiency according to the measured turbocharger performance maps. In conclusion, in comparison to measurements the simulation methodology provides reliable results and gives additional insights to the fluid-solid interactions and their governing heat transfer processes. Furthermore, the polyhedral calculation grid is beneficial to the convergence behavior and heat transfer assessment. The obtained results indicate further research potential with respect to transient turbocharger calculations and the consideration of the lubrication system for a validation of the heat transfer to the engine oil. Finally, it can be stated that the provided simulation approach has large potential for the dimensioning of the complex assemblies and will continue to grow in importance in the coming years.

KW - CFD

KW - AVL FIRE

KW - heat transfer

KW - turbocharger

KW - polyhedral mesh

KW - coupled simulation

KW - Moving Reference Frame

KW - BorgWarner S410 Euro4

KW - CFD

KW - AVL FIRE

KW - Wärmeübertragung

KW - Turbolader

KW - polygonales Berechnungsgitter

KW - gekoppelte Simulation

KW - Moving Reference Frame

KW - BorgWarner S410 Euro4

M3 - Master's Thesis

ER -