Heat Transfer Coefficient on Combustion Chamber Wall in a Naturally Aspirated D.I. Diesel Engine

Abstract

Using thin-film thermocouples, the authors measured instantaneous temperature at 99 points on all the combustion chamber wall surfaces of a naturally aspirated direct injection diesel engine. Instantaneous heat flux at each measured point was also obtained by heat transfer analysis based on the measured instantaneous wall surface temperature. In addition, the instantaneous gas temperature was calculated from the internal pressure of the combustion chamber. So that local and mean heat transfer coefficients could be evaluated with the corresponding wall surface temperatures and heat fluxes. The heat transfer coefficients were obtained for five ignition timings and three engine speeds.