Multi-physics investigation of diesel engine piston crown geometry for enhanced performance and emission reduction

• Optimizing piston crown geometry (flat-standard, semi-spherical, multi-spherical) in a V12 diesel engine to boost efficiency, power, torque, and reduce emissions/SFC. • Combined thermal/structural FEM analysis (custom MATLAB solver, validated vs. ANSYS) and combustion performance evaluation (Diesel-RK). • The multi-spherical crown design delivered optimal performance: 3.0% increase in power & torque, 3.5% reduction in specific fuel consumption (SFC). • Multi-spherical crown caused 38.9% PM reduction (better mixing) but increased NOₓ (higher temperatures). The overall emissions index dropped 38.87%, indicating a net environmental benefit. Advancements in engine technology demand optimized piston designs that enhance performance while reducing emissions. Among the critical factors, piston crown geometry strongly influences thermal stresses, combustion dynamics, and emission characteristics. This study evaluates the thermal, structural, and combustion behaviour of a 12-cylinder, V-type, direct-injection diesel engine using three piston crown configurations: flat-standard, semi-spherical, and multi-spherical. A custom finite element method (FEM) solver in MATLAB, validated against ANSYS results, is employed for thermal–structural analysis, while Diesel-RK is used for combustion and emission modelling. The objective is to identify the crown geometry that achieves higher efficiency and durability under realistic operating conditions. Results indicate that the multi-spherical crown provides the best overall performance, with a 2.96% increase in power and torque, a 3.49% reduction in specific fuel consumption, and a 38.9% decrease in particulate matter emissions compared to the flat-standard crown. Although NO ₓ emissions increase due to higher in-cylinder temperatures, the overall emissions index improves by 38.87%, confirming an environmental advantage. The findings establish a computationally efficient multi-physics framework for piston crown optimization and demonstrate the potential of optimized geometries to advance the development of durable, high-efficiency, and low-emission diesel engines.