Swirl-chamber indirect injection engines are widely used as small diesel engines for industrial applications. In order to improve the commercial potential of our products, Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. has applied an optimization design process coupling CFD and AI to the combustion chamber shape of swirl-chamber indirect injection engines for the first time. After defining the combustion and flow concepts for a swirl-chamber indirect injection engine, we coupled CFD and AI to automatically search for the optimal combustion chamber shape. Through analysis of the data obtained in the searching process, we selected the optimal combustion chamber shape and also confirmed that performance improvement was achieved as expected by actual equipment testing. In addition, by applying the optimized combustion chamber to the new L series engine under development, it was verified that the output range can be significantly expanded compared to an existing engine, while achieving a class-leading brake mean effective pressure (BMEP) and specific fuel consumption.
