Modeling of air-fuel mixture flow in a marine four-stroke diesel engine to optimize performance and minimize pollutant emissions

This study proposes a computational framework that utilizes advanced Computational Fluid Dynamics (CFD)-based modeling and diesel-cycle analysis to analyze the emissions and performance of a high-speed marine four-stroke diesel engine. A three-dimensional sector model is created with an emphasis on a Perkins 404D-22 engine that is typical of small craft and auxiliary maritime applications. A precise description of in-cylinder processes is provided by combining this model with thermodynamic metrics that have been extracted from simulation results utilizing ideal and actual Diesel cycle formulations. The influence of two running speeds, 2200, 3000 rpm, is measured as baseline conditions on indicated power, combustion and thermal efficiency, pollutant generation, and energy balance. The approach of 3000 rpm, which is applicable to real-world maritime duty profiles, received particular focus. Building on this, a methodical parametric study examines how engine behavior is affected by intake air temperature, intake pressure, and injected fuel mass. The parametric analysis quantifies the influence of intake air temperature, intake pressure, and injected fuel mass on combustion characteristics, thermal efficiency, gaseous and particulate emissions. The results demonstrate that proper speed and intake condition adjustment can reduce emissions and increase efficiency at the same time, but they also highlight application-dependent trade-offs between power, fuel consumption, and pollutant output. The proposed computational framework provides engineering guidance for the development of cleaner and more effective propulsion systems by illustrating how a combined CFD–Diesel cycle framework can support design and operation decisions for high-speed marine diesel engines under increasingly stringent IMO emission regulations.