Study on Combustion Chamber Geometry Effects in an HCCI Engine using High-Speed Cycle-Resolved Chemiluminescence Imaging
Author
Summary, in English
The aim of this study is to see how geometry generated
turbulence affects the Rate of Heat Release (ROHR) in
an HCCI engine. HCCI combustion is limited in load due
to high peak pressures and too fast combustion. If the
speed of combustion can be decreased the load range
can be extended. Therefore two different combustion
chamber geometries were investigated, one with a disc
shape and one with a square bowl in piston. The later
one provokes squish-generated gas flow into the bowl
causing turbulence. The disc shaped combustion
chamber was used as a reference case. Combustion
duration and ROHR were studied using heat release
analysis. A Scania D12 Diesel engine, converted to port
injected HCCI with ethanol was used for the
experiments. An engine speed of 1200 rpm was applied
throughout the tests. The effect of air/fuel ratio and
combustion phasing was also studied. The behavior of
the heat release was correlated with high speed
chemiluminescence imaging for both combustion
chamber geometries. Optical access was enabled from
beneath by a quartz piston and a 45 degree mirror. It
was found that the square bowl in piston generates
higher turbulence levels resulting in half the ROHR and
twice as long combustion duration as the disc shaped
combustion chamber. By using a resolution of 3 images
per CAD, the fast gas movements during the entire
HCCI combustion process could be studied inside the
bowl.
turbulence affects the Rate of Heat Release (ROHR) in
an HCCI engine. HCCI combustion is limited in load due
to high peak pressures and too fast combustion. If the
speed of combustion can be decreased the load range
can be extended. Therefore two different combustion
chamber geometries were investigated, one with a disc
shape and one with a square bowl in piston. The later
one provokes squish-generated gas flow into the bowl
causing turbulence. The disc shaped combustion
chamber was used as a reference case. Combustion
duration and ROHR were studied using heat release
analysis. A Scania D12 Diesel engine, converted to port
injected HCCI with ethanol was used for the
experiments. An engine speed of 1200 rpm was applied
throughout the tests. The effect of air/fuel ratio and
combustion phasing was also studied. The behavior of
the heat release was correlated with high speed
chemiluminescence imaging for both combustion
chamber geometries. Optical access was enabled from
beneath by a quartz piston and a 45 degree mirror. It
was found that the square bowl in piston generates
higher turbulence levels resulting in half the ROHR and
twice as long combustion duration as the disc shaped
combustion chamber. By using a resolution of 3 images
per CAD, the fast gas movements during the entire
HCCI combustion process could be studied inside the
bowl.
Department/s
Publishing year
2007
Language
English
Publication/Series
SAE Technical Paper Series
Full text
Document type
Working paper
Topic
- Other Mechanical Engineering
Keywords
- combustion chamber geometry
- Chemiluminescence
- HCCI
- Engine
Status
Published