Research of turbulent jet controlled premixed-diffusion cooperative combustion mode for a marine dual-fuel engine with pre-chambers

Diesel/natural gas dual-fuel technology is a promising solution for reducing NO x and greenhouse gas emissions of marine engines. However, conventional natural gas combustion struggles to achieve both high thermal efficiency and low NO x emission. To address this, the Turbulent Jet-Controlled Cooperative Combustion (TJCCC) mode is proposed, fully leveraging the complementary advantages of premixed combustion and diffusion combustion. Numerical simulations are conducted at 50% load to investigate the collaborative combustion mechanism of high-pressure natural gas (HPNG) and low-pressure natural gas (LPNG) under varying ratios. Compared to pure HPNG, this structure increases heat release intensity and combustion pressure but also raises NO x formation. At an LPNG ratio of 60%, the thermal efficiency reaches its maximum value of 53.5%. NOx rises initially with growing LPNG due to elevated in-cylinder temperature, then slightly falls from shortened high-temperature residence time. Overall, a higher LPNG ratio improves efficiency and reduces greenhouse gas emissions, though NO x emissions and peak in-cylinder pressure require strict control. The proposed TJCCC mode provides a feasible technical route for the development of high-efficiency and low-carbon marine dual-fuel engines, and can offer theoretical support for the combustion optimization of existing low-speed gas engines.