The phase-varying mechanism of the ion current observed in a Homogeneous Charge Compression Ignition (HCCI) engine is investigated to achieve ion current-based combustion phasing. By integrating the gasoline flame ionization mechanism with the HCCI combustion model, the mechanisms affecting the ion formation and recombination processes are analyzed, and the relationship between the phases of ion current and combustion event is studied. Modeling results indicate that the formation rate of H 3 O + ions is mainly affected by the combustion boundary conditions. However, the ion recombination rate of H 3 O + ions is mainly dependent on the concentration of these ions. In the presence of the above mechanisms, the phase-varying tendency of the ion current is found to be similar to the variations in the combustion phase, but the offset between these phases will vary when the combustion boundary condition changes. As the equivalence ratio becomes low, the rate of H 3 O + formation is decreased and the ion recombination rate decreases even more, due to the reduced ion concentration. Therefore, the inflection point of the ion current curve, dI max , is retarded even further compared to the combustion phase CA50. In addition, a larger phase offset between dI max and CA50 is observed when the intake temperature is lower. All of the above modeling predictions agree well with the experimental results.
History
School
Aeronautical, Automotive, Chemical and Materials Engineering
Department
Aeronautical and Automotive Engineering
Published in
Fuel
Volume
113
Pages
209 - 215
Citation
DONG, G. ... et al., 2013. Study of the phase-varying mechanisms of ion current signals for combustion phasing in a gasoline HCCI engine. Fuel, 113, pp.209-215.
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/
Publication date
2013
Notes
This work was supported by National Basic Research Priorities
Program (973) of China under the Grant reference of 2007CB
210005.