Study on ignition and combustion characteristics of prechamber ignition using rapid compression and expansion machine

Abstract

The prechamber combustion characteristics were studied using a rapid compression and expansion machine (RCEM) to improve the efficiency of cogeneration natural gas engines. The torch flames generated by a prechamber were used to investigate the effect that a prechamber has on the main combustion. In our previous study, we observed the correlation between the torch flame and the main flame (which is a so-called “prechamber combustion”). In this study, the effects of prechamber parameters such as initial pressure and nozzle diameter of injection holes, equivalence ratio on prechamber combustion characteristics were investigated in detail. Especially, by comparing the combustion characteristics of methane, which is the main component of natural gas, and propane, which is a representative of small-volume components, the effects of fuel types on the ignition and combustion characteristics of pre-chamber ignition system were investigated to elucidate of the effect of fuel property. In conclusions, regarding the mechanism of prechamber-ignition combustion, it was inferred that the jet erupted from the prechamber did not directly propagate in the main chamber but included the "ignition phenomenon" of the main chamber due to the jet. In addition, under the experimental conditions of this study, it was found that the ignition delay time and the combustion period can be predicted by simple calculation, which can lead to the important guideline for the pre-chamber design.

Keywords

• prechamber
• rcem
• ignition
• jet flame
• gas engine
• shadowgraph method