Swumble In-Cylinder Fluid Motion: A Pathway to High Efficiency Gasoline SI Engines

Autoren

Guillaume Bourhis, Dr. Olivier Laget, Rajesh Kumar, Xavier Gautrot,
IFP Energies nouvelles, Institut Carnot IFPEN Transports Energie, Rueil-Malmaison

Zusammenfassung

Global warming concerns, and emissions regulations require to improve internal combustion engine (ICE) efficiency and its emissions levels. Focusing on spark ignition engines, main trend is to increase compression ratio (CR) combined with the use of Miller/Atkinson cycle. One drawback of Miller/Atkinson cycle is the reduction of the in-cylinder fluid motion and thus a loss of turbulent kinetic energy (TKE), resulting in a decrease of the combustion speed and then a limitation of the engine efficiency gains. To improve this weakness, IFP Energies nouvelles (IFPEN) has been working on the development of a complex in-cylinder fluid motion so-called swumble. This is the combination of tumble, cross-tumble and swirl motion whereas current engines use mainly tumble fluid motion.

To develop a new engine using this innovative in-cylinder fluid motion, CFD calculations and tests on a single cylinder engine have been performed. By extrapolation from single cylinder results, the engine outputs of a three-cylinder engine are estimated.

Simulation results highlight the good adequacy when using such complex aerodynamic motion coupled with Miller/Atkinson cycles. There is nearly no impact of the valve opening duration on the production of TKE. Moreover, test bench results confirm the nearly constant combustion speed when using different level of Miller cycle. A greater capacity for dilution and a reduction of the emitted particles are also demonstrated. The optimal configuration is a 13:1 CR with a 140 CAD intake lift duration, taking benefits from IGR and EGR and using lambda one operation throughout the whole engine map. The extrapolated maximum output torque and power are respectively 175 N.m/L and 70 kW/L with a peak brake efficiency of 42 %. In addition, brake efficiency higher than 40 % covers a significant area of the engine map.

This paper details the different steps of this development. Further improvements of this swumble motion approach are currently under progress to make it applicable for different architectures and engine capacities.

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