Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics
- Department of Chemical Engineering and Biotechnology, University of Cambridge (United Kingdom)
- Department of Engineering, University of Cambridge (United Kingdom)
This paper presents experimental results and a new computational model that investigate cycle to cycle variations (CCV) in a spark ignition (SI) engine. An established stochastic reactor model (SRM) previously used to examine homogeneous charge compression ignition (HCCI) combustion has been extended by spark initiation, flame propagation and flame termination sub-models in order to simulate combustion in SI engines. The model contains a detailed chemical mechanism but relatively short computation times are achieved. The flame front is assumed to be spherical and centred at the spark location, and a pent roof and piston bowl geometry are accounted for. The model is validated by simulating the pressure profile and emissions from an iso-octane fuelled single cylinder research engine that showed low CCV. The effects of key parameters are investigated. Experimental results that show cycle to cycle fluctuations in a four-cylinder naturally aspirated gasoline fuelled SI engine are presented. The model is then coupled with GT-Power, a one-dimensional engine simulation tool, which is used to simulate the breathing events during a multi-cycle simulation. This allows an investigation of the cyclic fluctuations in peak pressure. The source and magnitude of nitric oxide (NO) emissions produced by different cycles are then investigated. It was found that faster burning cycles result in increased NO emissions compared with cycles that have a slower rate of combustion and that more is produced in the early stages of combustion compared with later in the cycle. The majority of NO was produced via the thermal mechanism just after combustion begins. (author)
- OSTI ID:
- 21396170
- Journal Information:
- Combustion and Flame, Vol. 158, Issue 1; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NITRIC OXIDE
COMBUSTION
FLUCTUATIONS
SPARK IGNITION ENGINES
COMPUTERIZED SIMULATION
OCTANE
EMISSION
GASOLINE
SPHERICAL CONFIGURATION
FLAMES
IGNITION
COMBUSTION KINETICS
CALCULATION METHODS
FLAME PROPAGATION
ONE-DIMENSIONAL CALCULATIONS
STOCHASTIC PROCESSES
PEAKS
PARAMETRIC ANALYSIS
Detailed chemistry
Cycle to cycle variation