Assessment of Diesel Engine Size-Scaling Relationships

Engine development is both time consuming and economically straining. Therefore, efforts are being made to optimize the research and development process for new engine technologies. The ability to apply information gained by studying an engine of one size/application to an engine of a completely different size/application would offer savings in both time and money in engine development. In this work, a computational study of diesel engine size-scaling relationships was performed to explore engine scaling parameters and the fundamental engine operating components that should be included in valid scaling arguments. Two scaling arguments were derived and tested: a simple, equal spray penetration scaling model and an extended, equal lift-off length scaling model. The simple scaling model is based on an equation for the conservation of mass and an equation for spray tip penetration developed by Hiroyasu et al. [1]. The extended scaling model includes the previous two equations as well as an equation for flame lift-off length developed by Pickett et al. [2]. The focus of the study was to apply these scaling hypotheses to new low emissions diesel engine operating regimes in order to determine the limits of the proposed scaling arguments and to assess the relative effects of chemical kinetics and turbulent mixing processes on combustion.