Combustion Diagnostics & Improvement of a Prechamber Lean-Burn Natural Gas Engine

This paper describes combustion process and characteristics of a natural gas fueled prechamber lean-burn gas engine. Using a 150mm-bore-sized visualization engine and a high-speed video camera with image intensifier, the structure and behavior of flame jet from the prechamber, flame propagation of lean mixture in the main chamber, and other combustion characteristics were investigated.

Simultaneous combustion analysis based on cylinder pressure, image analysis, and single-cylinder engine operations with exhaust gas sampling were also performed to bring about a better understanding of observed image. Multi-cylinder engine operation was also performed to validate the effect of combustion improvement technique that was found from the knowledge of diagnostic results. Image analysis results were also compared with those of spark ignition combustion in the same visualization engine.