Full Cycle CFD Simulations to Study Thermal and Chemical Effects of Fuel Injection during Negative Valve Overlap in an Automotive Research Engine

2010 ◽  
Author(s):  
Randy P. Hessel ◽  
Richard Steeper ◽  
Russell Fitzgerald ◽  
Salvador Aceves ◽  
Daniel Flowers
Keyword(s):  
Fuel Injection ◽  
Cfd Simulations ◽  
Chemical Effects ◽  
Negative Valve Overlap ◽  
Valve Overlap

Effect of Fuel Injection Timing During Negative Valve Overlap Period on a GDI-HCCI Engine

2018 ◽  
Author(s):  
Sok Ratnak ◽  
Jin Kusaka ◽  
Yasuhiro Daisho ◽  
Kei Yoshimura ◽  
Kenjiro Nakama
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Single Pulse ◽  
Injection Timing ◽  
Pulse Injection ◽  
Hcci Combustion ◽  
Fuel Injection Timing ◽  
Intake Stroke ◽  
Negative Valve Overlap ◽  
Valve Overlap

Gasoline Direct Injection Homogeneous Charge Compression (GDI-HCCI) combustion is achieved by closing early the exhaust valves for trapping hot residual gases combined with direct fuel injection. The combustion is chemically controlled by multi-point auto-ignition which its main combustion phase can be controlled by direct injection timing of fuel. This work investigates the effect of single pulse injection timing on a supercharged GDI-HCCI combustion engine by using a four-stroke single cylinder engine with a side-mounted direct fuel injector. Injection of primary reference fuel PRF90 under the near-stoichiometric-boosted condition is studied. The fuel is injected during negative valve overlap (NVO) or recompression period for fuel reformation under low oxygen concentration and the injection is retarded to intake stroke for the homogeneous mixture. It is found that the early fuel injection in NVO period advances the combustion phasing compared with the retarded injection in the intake stroke. Noticeable slower combustion rate from intake stroke fuel injection is obtained compared with the NVO injection due to charge cooling effect. Zero-dimensional combustion simulations with multiple chemical reaction mechanisms are simulated to provide chemical understanding from the effect of fuel injection timing on intermediate species generations. The species such as C2H4, C3H6, CH4, and H2 are found to be formed during the NVO injection period from the calculations. The effects of single pulse injection timings on combustion characteristics such pressure rise rate, combustion stability, and emissions are also discussed in this study.

Study on knocking combustion in a diesel HCCI engine with fuel injection in negative valve overlap

Fuel ◽  
2013 ◽  
Vol 106 ◽  
pp. 478-483 ◽  
Author(s):  
Lei Shi ◽  
Kangyao Deng ◽  
Yi Cui ◽  
Shuan Qu ◽  
Wei Hu
Keyword(s):  
Fuel Injection ◽  
Hcci Engine ◽  
Negative Valve Overlap ◽  
Valve Overlap

scholarly journals Numerical investigation into the effect of direct fuel injection on thermal stratification in HCCI engine

2017 ◽  
Vol 169 (2) ◽  
pp. 137-140
Author(s):  
Michał GĘCA ◽  
Jacek HUNICZ ◽  
Piotr JAWORSKI
Keyword(s):  
Combustion Chamber ◽  
Thermal Stratification ◽  
Fuel Injection ◽  
Injection Timing ◽  
Ignition Timing ◽  
Hcci Engine ◽  
Auto Ignition ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Direct Fuel Injection

Despite the fact that HCCI engines are distinguished by mixture homogeneity, some degree of stratification always appears inside a combustion chamber. It is especially applied to residual effect engines utilizing negative valve overlap. Mixture stratification is a result of the imperfect mixing of fresh air with trapped residuals. Direct fuel injection introduces stratification as well, due to fuel vaporization. As a consequence, the temperature within the combustion chamber is uneven. Thermal stratification affects auto-ignition timing and combustion evolution in a high extent. The purpose of this study was to evaluate a degree of thermal stratification in HCCI engine utilizing negative valve overlap. Investigations were performed using three-dimensional CFD model of the combustion system, made by using AVL FIRE software. Simulations were realized for various timings of fuel injection into the cylinder. It was found that fuel injection timing had a significant effect on the thermal stratification and resulting auto-ignition timing.

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