A study of the local heat transfer coefficient on the combustion chamber walls of a 4-stroke gasoline engine.

Abstract

It is said that coefficients of heat transfer on combustion chamber walls of internal combustion engines differ according to individual locations, but no actual measurements have been reported. This study determined the coefficient of local heat transfer at each location on the wall surfaces of a combustion chamber obtained by the instantaneous temperature Tw and the instantaneous heat flux q at each location measured by highly accurate thin film thermocouples developed by the authors, and the instantaneous gas temperature Tg in the combustion chamber determined by the gas pressure P in the combustion chamber, the only source of information on gas in the chamber. As a result, it was found that the engine speed, gas flow, ignition timing, distance from the plug, shape of combustion chamber, temperature, etc. would affect significantly on the local heat transfer coefficient. It was also found that Eichelberg's equation or Woschni's equation in which the gas flow is taken into account would yield substantial differences from measured values in the high engine speed range.