scholarly journals Effects of fuel composition and engine operating conditions on particle number index in a direct injection spark ignition engine

2021 ◽  
Vol 243 ◽  
pp. 114428
Author(s):  
Ziyoung Lee ◽  
Sungwook Park
Keyword(s):  
Particle Number ◽  
Direct Injection ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Fuel Composition ◽  
Direct Injection Spark Ignition

CFD modeling of pre-spark heat release in a boosted direct-injection spark-ignition engine

2021 ◽  
pp. 146808742110441
Author(s):  
Hengjie Guo ◽  
Roberto Torelli ◽  
James P Szybist ◽  
Sibendu Som
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Direct Injection ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Detailed Chemistry ◽  
Direct Injection Spark Ignition

Accurate predictions of low-temperature heat release (LTHR) are critical for modeling auto-ignition processes in internal combustion engines. While LTHR is typically obscured by deflagration, extremely late ignition phasing can lead to LTHR prior to the spark, a behavior known as pre-spark heat release (PSHR). In this research, PSHR in a boosted direct-injection spark-ignition engine was studied using 3-D computational fluid dynamics (CFD) and detailed chemical kinetics. The turbulent combustion was modeled via a hybrid approach that incorporates the G-equation model for tracking the turbulent flame front, and the well-stirred reactor model with detailed chemistry for assessing the low-temperature reactions in unburnt gas. Simulations were conducted using Co-Optima alkylate and E30 fuels at operating conditions characterized by different PSHR intensities. The predicted in-cylinder pressure and heat release rate were found to agree well with experiments. It was found the estimate of previous-cycle trapped residuals is of utmost importance for capturing PSHR correctly. A simulation best practice was developed which keeps the detailed chemistry solver active throughout the entire simulation, allowing to track the evolution of intermediate species from one cycle to the next. Following the validation, the dynamics of PSHR were analyzed in detail employing the pressure-temperature (P-T) trajectory framework. It was shown that PSHR correlated with the first-stage ignition delay of the fuel, hence showing close relation to the in-cylinder P-T trajectory and the chemical kinetics. Besides, it was indicated that LTHR is a self-limiting process that has the effect of attenuating the thermal stratification in the combustion chamber. Furthermore, it was observed the occurrence of PSHR caused the P-T trajectory of end-gas to overlap with the negative temperature coefficient region of the fuel’s ignition-delay maps. This effect was more significant in the fuel-rich regions where engine knock tendency would be generally higher, with potential implications on knock control and mitigation.

Soot Development in an Optical Direct Injection Spark Ignition Engine Fueled with Isooctane

2021 ◽  
Vol 22 (2) ◽  
pp. 455-463
Author(s):  
Fangxi Xie ◽  
Miaomiao Zhang ◽  
Yongzhen Wang ◽  
Yan Su ◽  
Wei Hong ◽  
...  
Keyword(s):  
Direct Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Direct Injection Spark Ignition
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