Analysis of Piston Bowl Topologies in a Hydrogen-Powered Commercial Vehicle Engine: Impact on Thermal Load and Mixture Formation

The performance of hydrogen combustion engines can be significantly influ-enced by the geometry of the piston bowl. In this work, various piston bowl designs are explored to assess their effects on thermal load and mixture formation, all while main-taining a constant compression ratio. The engine, originally developed for commercial utility vehicles, has been specifically converted for hydrogen operation to accommodate the specific requirements of this fuel. Abstract piston bowl geometries are modeled and evaluated through Computational Fluid Dynamics (CFD) simulations using the commer-cial software AVL FIRE M. A validated operating point based on a reference piston bowl geometry serves as the basis for comparison. Piston bowl variations with shallower and deeper profiles are investigated to achieve an optimal compromise, leveraging the benefits of each design. Special attention is placed on flow quality and mixture formation when using hydrogen as fuel. Potential adverse effects observed in conventional piston bowl configurations could be mitigated due to hydro-gen’s exceptionally high diffusivity. This characteristic allows overcoming geome-try-induced drawbacks and emphasizes the positive aspects of particular bowl shapes. The study provides a comprehensive understanding of how piston bowl topology influ-ences thermal load, mixture formation, and flow quality in the context of hydrogen com-bustion engines.