Performance of combustion process on marine low speed two-stroke dual fuel engine at different fuel conditions: Full diesel/diesel ignited natural gas

In order to deeply understand the combustion process of marine low speed two-stroke dual fuel engine under the background of "carbon neutrality", MAN B&W 6S50ME-C-GI was taken as the research object, combustion processes of the full diesel (FD) and diesel ignited natural gas (DING) at 100 % load were tested and calculated. The results show that the total combustion duration period (CDP) under DING is 15.5 degrees CA shorter than that under FD. The slow combustion period (SCP) and post combustion period (PCP) under DING were 1.75 degrees CA and 15 degrees CA lower than those under FD, respectively. At the same combustion time, the local high temperature region under DING is reduced by an average of 8 % compared with FD. The radial flame propagation velocity under DING and FD showed a "single peak" law, and the axial flame propagation velocity shows a "fluctuation" law. The difference is that the radial flame propagation velocity under FD shows attenuation to zero twice at 8 degrees CA ATDC and 14 degrees CA ATDC, and the flame propagation velocity of natural gas combustion is faster than that of diesel combustion. The maximum radial flame propagation velocity under DING is 2.5 m/s faster than that under FD. The maximum axial flame propagation velocity under DING is 0.7 m/s faster than that under FD.