Hamidreza Chamani - Iran heavy diesel engine. Mfg. Co(DESA)
Mazdak Jafarabadi - Iran heavy diesel engine. Mfg. Co (DESA)

In recent years, the demand for higher specific power has enforced higher operating temperatures on engine parts which have a significant effect on thermo mechanical loading and consequently on mechanical damage. The Cylinder head is one of the critical components of the diesel engine that is subjected to complicated thermal and mechanical loadings. Temperature distribution and temperature gradient lead to thermal stress and thermo-mechanical fatigue of Cylinder head. Thus, an accurate and fast method is required in order to obtain correct temperature distribution of such critical component. In this study, a detail discussion on thermal loadings of cylinder head and the procedure to determine theaccurate temperature distribution of it are discussed. A coupled thermal and CFD analysis of water jacket cooling is performed and the effect of nucleate boiling on heat flux is considered. The subcooled nucleate boiling heat transfer computation is carried out using the boiling departure lift-off (BDL) model, in which the total heat flux is assumed to be additively composed of a forced convective and a nucleate boiling component. It is observed that at hot spots, nucleate boiling occurs for low coolant flow regions specifically around the cylinder head’s exhaust port and liner coolant side wall.

Diesel engine, Cylinder head, Thermal analysis, Subcooled boiling