This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Effect of Fuel and Thermal Stratifications on the Operational Range of an HCCI Gasoline Engine Using the Blow-Down Super Charge System
Journal Article
2010-01-0845
ISSN: 1946-3936, e-ISSN: 1946-3944
Sector:
Topic:
Citation:
Kuboyama, T., Moriyoshi, Y., Hatamura, K., Suzuki, M. et al., "Effect of Fuel and Thermal Stratifications on the Operational Range of an HCCI Gasoline Engine Using the Blow-Down Super Charge System," SAE Int. J. Engines 3(1):666-680, 2010, https://doi.org/10.4271/2010-01-0845.
Language:
English
Abstract:
In order to extend the HCCI high load operational limit, the
effects of the distributions of temperature and fuel concentration
on pressure rise rate (dP/dθ) were investigated through theoretical
and experimental methods. The Blow-Down Super Charge (BDSC) and the
EGR guide parts are employed simultaneously to enhance thermal
stratification inside the cylinder. And also, to control the
distribution of fuel concentration, direct fuel injection system
was used.
As a first step, the effect of spatial temperature distribution
on maximum pressure rise rate (dP/dθmax) was investigated. The
influence of the EGR guide parts on the temperature distribution
was investigated using 3-D numerical simulation. Simulation results
showed that the temperature difference between high temperature
zone and low temperature zone increased by using EGR guide parts
together with the BDSC system. Experiments were conducted by using
a four-cylinder gasoline engine equipped with the BDSC with EGR
guide system to investigate the effect of the EGR guide on the heat
release rate and the in-cylinder pressure rise rate. Experimental
results showed that 50% and 90% mass fraction burned timing (CA50
and CA90) were delayed and combustion duration became longer when
the EGR guide was used to enhance thermal stratification. As a
result, the maximum pressure rise rate could be decreased and the
HCCI high load limit successfully extended. Meanwhile 10% mass
fraction burned timing (CA10) was not affected by the thermal
stratification generated by the EGR guide. This is probably because
the fuel is also spatially stratified such that the fuel
concentration becomes lean in the high temperature zone.
Next, the effect of the fuel distribution on high load HCCI
operation was investigated. Numerical analysis using a multi-zone
combustion model considering detailed chemical reactions was
carried out. The simulation results showed that the maximum
pressure rise rate was decreased by 27% when the fuel distribution
was uniform with temperature distribution generated by the BDSC
with EGR guide system. Then, to obtain a uniform fuel distribution
while keeping the temperature distribution generated by the BDSC
with EGR guide system, a direct injection system was employed and
the effect of fuel direct injection on maximum pressure rise rate
was experimentally investigated. As a result, if 20% of the total
fuel was injected directly into the cylinder during the exhaust
stroke, the spatial distribution of the fuel concentration (G/F;
fuel mass ratio to the total mass of in-cylinder mixture) became
more homogeneous and maximum pressure rise rate was decreased by
10%. And also, 20% of the total fuel directly injected during the
compression stroke, maximum pressure rise rate was decreased by
20%.
Finally, a simple method to predict the ignition timing using
Livengood-Wu integral and 1-D numerical simulation code was
examined. It was found that the proposed method can predict the
ignition timing with small deviation around ±2 degrees.