CFDModeling of Diesel Combustion

Abstract

Diesel engines are the most efficient combustion engines today, playing an important role in transport of goods and passengers on land and on sea. The main drivers for the design of future engines is the control of the emissions without sacrificing their advanced fuel economy. These drivers led to important innovations in multiple components of the engine, which, however, complicated the nature of the processes taking place and increased the need for highly accurate simulation frameworks. In the current article, the focus is on the recent progress of combustion modeling of diesel engines. The major general challenges encountered are first introduced briefly and then the progress in various research areas is reported in more details. Special focus is given to the most commonly used combustion models describing their advantages as well as their shortcomings. In the end, some closing remarks are presented as guidelines for future modeling efforts.

Spillback nozzle characterization using pulsating LED shadowgraphy

“…The average sample size needed to meet the error threshold was calculated (Figure 4b) and the process was repeated for thresholds from 1 to 10%. The results of this analysis show that the number of droplets needed to have a reasonably accurate estimate (2 to 4% relative error) of the SMD is between 10 4 and 4x10 4 , while to obtain similar uncertainties on the mean droplet velocity less than a tenth of these amounts are sufficient.…”

“…This analysis showed that the average sample size needed to achieve a certain error is not influenced by the original sample size in the observed range (Figure 7). A more complex behaviour is observed for the SMD, but it is possible to observe that for errors above 2%, the estimate converge for a population around 8x10 4 . This again confirms that the sample used is large enough to draw conclusions above this error threshold.…”

“…The work presented in this paper is a study aimed at obtaining further insight into spray characteristics in this type of system. The interactions between atomization and combustion process can be described by Computational Fluid Dynamics models [4]. However, when applying this method to a full-scale system, the spatial discretization needed to observe the first stages of the atomization process is much smaller than the other characteristics lengths [5].…”