Thermal Modelling of a Marine Diesel Engine Piston

This work presents a computational thermal analysis of a 4-ring articulated piston of a marine diesel engine for determining the temperature distribution of piston head. The temperature distribution is the basis of calculating thermal stresses and deformations and subsequent identification of their largest value locations. The piston model is developed in CATIA V5R19 and exported to ANSYS for finite element analysis. The input parameters are gas temperature, cooling water temperature and oil temperature, whereas the boundary conditions given in the analysis are coefficients of heat transfer (CoHTs) and heat flux. COHTs vary radially on the piston head and these values are calculated using Seal's formula. The piston top surface is divided into ten sub-regions of equal intervals and the thermal analysis results show that there are temperature variations on piston top surface where the 5-6-7-8 sub-regions have the highest temperature range of 603.59-632.91K. The temperature of the first four regions gradually increases and their temperature range value is 486.31-603.59 K. In the remaining two sub-regions the temperatures were found to be in the range of 544.95-603.59K. The piston skirt has the minimum temperature range of 369.03-398.35K since it is far from combustion. The total heat flux pattern closely follows that of the temperature. The results obtained will help in enhancing the piston design in the future for more safety and longer life.