Effect of Turbulence on HCCI Combustion 2007-01-0183
This paper presents large eddy simulation (LES) and experimental studies of the combustion process of ethanol/air mixture in an experimental optical HCCI engine. The fuel is injected to the intake port manifolds to generate uniform fuel/air mixture in the cylinder. Two different piston shapes, one with a flat disc and one with a square bowl, were employed to generate different in-cylinder turbulence and temperature field prior to auto-ignition. The aim of this study was to scrutinize the effect of in-cylinder turbulence on the temperature field and on the combustion process. The fuel tracer, acetone, is measured using laser induced fluorescence (LIF) to characterize the reaction fronts, and chemiluminescence images were recorded using a high speed camera, with a 0.25 crank angle degree resolution, to further illustrate the combustion process. Pressure in the cylinder is recorded in the experiments. Spatial and temporal resolved LES was used to gain information on the turbulence mixing, heat transfer and combustion process. It was shown that gas temperature in the piston bowl is generally higher than that in the squish, leading to an earlier ignition in the bowl. Compared to the disc engine, the square bowl engine has a higher temperature inhomogeneity owing to the turbulence wall heat transfer. The experimentally observed higher combustion duration and slower pressure rise rate in the square bowl engine as compared to the disc engine can be explained by the higher temperature inhomogeneity in the square bowl engine.
Author(s):
R. X. Yu, X. S. Bai, A. Vressner, A. Hultqvist, B. Johansson, J. Olofsson, H. Seyfried, J. Sjöholm, M. Richter, M. Aldén
Affiliated:
Division of Fluid Mechanics, Lund Institute of Technology, Division of Combustion Engines, Lund Institute of Technology, Division of Combustion Physics, Lund Institute of Technology
Pages: 15
Event:
SAE World Congress & Exhibition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Homogeneous Charge Compression Ignition Engines, 2007-SP-2100, SAE 2007 Transactions Journal of Engines-V116-3
Related Topics:
HCCI engines
Combustion and combustion processes
Heat transfer
Manifolds
Engine cylinders
Pistons
Turbulence
Ethanol
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