Large HSDI CR diesel engines multiple injections and multiple swirls concept

All future power developments should consider as primary tasks the achievement of the required emission levels and CO2-values, while still providing optimum torque-to-rpm curves, the lowest SFC (Specific Fuel Consumption) over the widest range possible, good power-to-weight and affordable costs. One method to achieve these objectives is the downsizing. To achieve the levels of engine performance that are required, a significant increase in the rated speed and in the boost pressure is mandatory. In this case, the result is an increase in the flow rate through the intake and exhaust ports and valves. Considering the impact of these changes, the port layout of the system is reanalyzed. Another physical limit to the maximum speed depends on the CR (Common Rail) injector dynamic performances. These performances decrease with size for inertia problems and they depend on the amount of effort involved in their development. Automotive engines in the range of 10 to 100 HP per cylinder are the most common. For this reason, these injectors are the most advanced and costeffective. Furthermore, their small size and inertia is favorable to the best dynamic performance. The larger number of nozzles improves combustion performance. In fact the better surface to volume ratio or the spray improves heat transfer. For this reason, multiple injection systems can be used in the modern HSDI (High Speed Direct Injection) CR large diesels. This solution was commonplace before WWII, but has been progressively abandoned with the introduction of mechanical high-pressure injection systems and the bowl combustion chamber. In this paper, a dual combustion chamber per cylinder engine is considered. The primary purpose of this study is to examine the best port layout on a modern diesel combustion system and to introduce a new promising concept. The study included flow measurements of intake flow and CFD simulations of the flow field during intake. This design enables the formation of two homogenous swirls centered onto the injectors, with excellent flow coefficient. The design also allows an increase in volumetric efficiency combined with a reduction in flow losses. © 2006-2015 Asian Research Publishing Network (ARPN).