| Abstract:In order to research the effect of pre-chamber system to development of flame jet, in-cylinder flow, combustion process and generation of emission, based on Computational Fluid Dynamics （CFD） program and chemical reaction kinetics, this paper built a numerical model of a large low-speed dual fuel marine engine modified by a normal diesel marine engine and explored the effect of different position cases of pre-chamber. The results show：When pre-chamber case cause flame jet collide, the flow field of colliding area is disturbed strongly, it also takes fuel rich mixed gas to this area, which restrains the generation of oxynitride（NOx）; If there is no collision between jet flame, the flame jet penetration will be longer and combustion achieve wider region multi-spot ignition in cylinder, which make heat release more focused, however it also brings higher level NOx emission. Besides, contact with wall such as cylinder head, liner, piston crown, will reduce the rate of jet flow observably.It also leadstoreducing of combustion temperatureandturbulentkinetic energyin cylinder, even causes combustion deterioration, which should be avoid. |