Elias Chalhoub and August Skoglund presents their master’s thesis

Student: Elias Chalhoub and August Skoglund
Main Supervisor: Isak Jonsson (Chalmers) and Sonny Andersson (GKN)
Examiner: Valery Chernoray
Opponent: Ivar Acevedo and Simon Duda

Abstract

Employing liquid hydrogen imposes certain engineering challenges, one of which is the design on the turbine rear structure part (TRS) of the aero engine. As liquid hydrogen has to be kept at low temperatures in order to remain in its liquid state and as the air exiting an engine is typically very hot this opens the possibility, if not necessity of heat exchange between the fluids. A model of a heat exchanger that can be used for this purpose was constructed by GKN and tested at Chalmers University of technology where the hydrogen was replaced by heated water. A patent for the heat exchanger model had been filed but not obtained during the thesis work which meant that the exact geometry of it was omitted from the thesis.

In this thesis the tests at Chalmers were used to perform CFD simulations of the turbine rear structure with an integrated heat exchanger. The results obtained from the CFD were then validated by comparing turbulence models and boundary condition specification methods after which the results were compared to the test data. The validity of the used CFD model was confirmed using tests and reasoning although the CFD model was shown to over predict the magnitude of separation zones. The measured outlet temperature of the water was shown to be accurately predicted by the CFD simulations. Finally the performance of the heat exchanger was assessed by calculating its effectiveness for the different simulations which gave indications for the optimal air flow.