Understanding the Dynamic Evolution of Cyclic Variability at the Operating Limits of HCCI Engines with Negative Valve Overlap 2012-01-1106
An experimental study is performed for homogeneous charge compression ignition (HCCI) combustion focusing on late phasing conditions with high cyclic variability (CV) approaching misfire. High CV limits the feasible operating range and the objective is to understand and quantify the dominating effects of the CV in order to enable controls for widening the operating range of HCCI. A combustion analysis method is developed for explaining the dynamic coupling in sequences of combustion cycles where important variables are residual gas temperature, combustion efficiency, heat release during re-compression, and unburned fuel mass. The results show that the unburned fuel mass carries over to the re-compression and to the next cycle creating a coupling between cycles, in addition to the well known temperature coupling, that is essential for understanding and predicting the HCCI behavior at lean conditions with high CV.
Citation: Hellström, E., Stefanopoulou, A., Vavra, J., Babajimopoulos, A. et al., "Understanding the Dynamic Evolution of Cyclic Variability at the Operating Limits of HCCI Engines with Negative Valve Overlap," SAE Int. J. Engines 5(3):995-1008, 2012, https://doi.org/10.4271/2012-01-1106. Download Citation
Erik Hellström, Anna Stefanopoulou, Jiri Vavra, Aristotelis Babajimopoulos, Dennis N. Assanis, Li Jiang, Hakan Yilmaz
University of Michigan, Robert Bosch LLC
SAE 2012 World Congress & Exhibition
SAE International Journal of Engines-V121-3EJ, SAE International Journal of Engines-V121-3, Kinetically Controlled IC Combustion, 2012-SP-2332