Numerical simulation and optimization of injector and nozzle pattern of an opposed-piston two-stroke diesel engine

Opposed-Piston Two-Stroke (OP2S) diesel engine shows high-power density, low heat transfer loss and good balance performance. However, side-mounted injectors must be used because of their special architecture, which makes it necessary to redesign the injector. In this paper, the effects of injector nozzles arrangement, including the number of injectors, the number of nozzles and their installation position, on the mixing and combustion performance were studied by using CFD simulation. Results show that the distribution of the equivalence ratio was significantly influenced by the effects of in-cylinder swirl and injection pattern. This swirl-induced interaction among gaseous fuel, leading to their aggregation, subsequently affects the combustion rate. An adequate space among the injector nozzles is essential for improving air utilization and combustion process. Altering the injector mounting angle allowed for the exploitation of in-cylinder micro-tumble, which could enhance droplet breakup and subsequently improved the mixing and combustion processes, and the Indicated Mean Effective Pressure (IMEP) could be increased by 6.42% compared to the prototype engine, yet with fewer injectors.