Flow-Structures generated by Valve and Piston Motion in an Exhaust Port of a Truck Engine

Författare: Wang, Y. W., Semlitsch, B., Mihaescu, M, Fuchs, L.F.
Dokumenttyp: Konferens
Tillstånd: Publicerad
Tidskrift: Proc. of the Int. Conf. on Jets, Wakes and Separated Flows, ICJWSF-2013
År: 2013


The exhaust port of a truck internal combustion engine forms the interface between the combustion engine and the turbocharger. Approximately 30-40% of the energy potential is lost in the exhaust gasses after combustion, which can be partially recuperated in a turbocharger. Hence, energy losses in the connection are highly undesired. However, due to the high occurring velocities and the complex geometry, flow separation, flow-structure formation, and secondary flow motion are the major sources of energy losses. Within the exhaust process, the valves open while the piston continues moving in the combustion camber. This process is often analyzed modeling the piston and valves at fixed locations, but conserving the total mass flow. Using advanced methods, this process can be simulated numerically in a more accurate manner. This study compares Large Eddy Simulations assessing the implied differences due to the methodical of simulating the exhaust process from an engine cylinder. A simple case using fixed positions for valve and piston is contrasted with the cases of static valve and moving piston, and moving valve and moving piston. The generated flow phenomena are compared within the cases.