CHT-analysis of rotor-stator system including radiation

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Presented at the STAR Global Conference 2012.

Increasingly “life-time prediction” is an important focus of the turbocharger development process. With this in mind, as a consequence of the high thermo-mechanical loads to which the turbocharger system is exposed, the turbine impeller is a critical component.

Conjugate Heat Transfer (CHT) simulation is performed for a stationary, high-load operation point of a diesel engine. The CHT model includes both, the flow through the turbine volute and the flow through the turbine impeller domain including the gap between backside of impeller and heat shield. Gas leakage is taken into account as it influences the temperature field.

The considered CHT model represents a rotor-stator system. The effect on the flow field of the rotating domain can be treated with different numerical approaches. An appropriate method to simulate region motion for a steady-state analysis is the moving reference frame (MRF) approach.

The problem of relative positioning is overcome by using an indirect mixing-plane-interface in order to couple the rotor and stator regions. Flow conditions on either side of the mixing-plane interface are averaged circumferential and relevant flow information are exchanged between rotating and non-rotating domain.

In STAR-CCM+ the radiation model is not compatible with mixing-plane interface. In order to account for heat transfer by radiation an alternative solution has to be developed. One possibility is to drop the mixing-plane interface, resulting in a numerically decoupling of rotating and non-rotating domain. The necessary exchange of flow field variables between both domains has to be done by user interaction.

The essence of this work is to establish a methodology to carry out CHT simulations with consideration of radiation in a complex geometry of a rotor-stator system.

Author Company: 
MTU Friedrichshafen
Author Name: 
Alexander Shvorak
J. Wildhagen
Vinod Malapure