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

Abstract

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°CA shorter than that under FD. The slow combustion period (SCP) and post combustion period (PCP) under DING were 1.75°CA and 15°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°CA ATDC and 14°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.