A Numerical Study on Diesel Engine Size-Scaling in Low Temperature Combustion Operation

A numerical study was conducted for diesel engine size-scaling in the low temperature combustion regime. Conventional scaling models were found to be inadequate for the low temperature combustion regime where chemical time scales become very important. Equal-time scaling was suggested to ensure the same chemical time scale for the scaled engines. With this approach, combustion phasing was well matched. However, peak in-cylinder pressure was higher in the upscaled engine, which is attributed to more homogeneous mixture conditions due to smaller surface to volume ratio (i.e., less wall friction). The overly enhanced mixing can be compensated with lower injection velocity.