(1-13) Heat Transfer in Diesel Engines : A CFD Evaluation Study((DE-4)Diesel Engine Combustion 4-Modeling)

Abstract

This study is concerned with the CFD prediction of wall heat transfer in reciprocating engines, with particular reference to Diesel engines working at high peak pressures (HPP), where accurate predictions of metal component thermal and pressure loadings are required. To this end, CFD simulations are performed of flow, combustion and heat transfer in a prototype HPP Diesel engine for which detailed local time-resolved surface heat transfer measurements have been performed. Comparisons are made between these data and predictions based on two wall heat transfer treatments, one of which ignores the effects of variations of thermophysical properties within the boundary layer and another which takes them into account. The latter treatment is shown to produce substantially better agreement than the former. It is also demonstrated that conventional widely-used empirical heat transfer correlations are incapable of providing the required levels of accuracy and detail. Finally, it is shown that local heat transfer measurements also provide a stringent testing ground for spray and combustion model performance.