Description
Master thesis by Christian Ahl JægerAbstract:
Research and development of large two-stroke marine diesel engines is expensive and time consuming. Reduction of time and cost are potentially gained with the use of computational fluid dynamics simulations. Setup and running of in-cylinder simulations is no simple task and requires expert knowledge within CFD. To simplify in-cylinder simulations, Siemens released the add-on package Star-ICE, which automates and simplifies in-cylinder setup and running.
This thesis is conducted entirely in Star-ICE where a single cylinder in-cylinder simulation was created based on MAN Energy Solutions 4T50ME-X test engine. The ease of use and adaptation of the automated setup was investigated on normal swirl, high swirl, and full cycle setups. Full cycle simulation was investigated with the Star-ICE ”simple” ECFM-CLEH combustion model. Furthermore was the numerical performance and accuracy investigated for potential reductions in computation time. Performance investigations were done through comparison to a similar Star-ccm+ in-cylinder model where several test cases were compared.
Star-ICE was shown to yield good results through validation of velocities, mass flow, and pressure compared to experimental results. The model was further used to investigate the correlation between initial conditions and full cycle results, which showed good agreement. Several implementations of transient exhaust boundaries were investigated indicating possible accuracy gains over the use of constant exhaust boundaries. Finally, the numerical comparison of Star-ICE and Star-ccm+ showed on-par results for raw performance. The comparison showed the benefit of using the simulation operation in Star-ICE over Java run file in Star-ccm+ with a total run time reduction of 60% due to dynamic time stepping.
| Period | 1 Mar 2021 |
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