Combustion Stability of Natural Gas Engine Operating at Idle

To investigate the combustion stability in a natural gas engine at idle, the burn parameters are determined on a cycle-by-cycle basis through the analysis of the engine pressure data. Combustion analysis based on cylinder-pressure provides a mechanism through which a combustion researcher can understand the combustion process. The parameters lowest normalized value (LNV) introduced by Hoard and Rehagen and coefficient of variation (COV) are used to investigate the combustion stability at idle. Measurements of combustion pressure are used to determine values for these parameters in a Ricardo research engine. The fuel used natural gas, and compression ratios between 6 and 14 are explored. The objective of this work is to identify whether these variables are a significant source of cycle-by-cycle combustion variability in a natural gas engine at idle.