Numerical Research on Effects of Variable Port Timing on Performance of Marine Low-Speed Two-Stroke Engine

Enhancing the effective expansion ratio to further improve fuel consumption, this study implemented a kind of Variable Port Timing (VPT) by designing vertically moving sleeve on outside scavenging port low-speed two-stroke diesel engine with 340 mm bore. A 3D Computational Fluid Dynamics (CFD) model was constructed and calibrated investigate influence VPT strategy performance internal gas exchange process. The results indicated that can reduce negative work from compression stroke increase stroke, which effectively enhances economy. However, reduction in mass flow rate would lead severe deterioration turbocharging system’s performance. related matching analysis between ports revealed velocity had minimal rate, while increasing height restore certain but will decrease in-cylinder swirl intensity, deteriorating combustion cylinders. optimal approach is raise position port, achieving Scavenging Closing (SPC) at 235°CA, original level 90.7% consumption 2.9 g/kWh.