In this study, we investigated a method of estimating the piston temperature in reciprocating engines. The piston temperature is strongly affected by the cylinder temperature distribution and in-cylinder turbulence. For that reason, it is necessary to take into account the effects of cooling by the intake air flow, the process of the temperature rise due to combustion, in-cylinder flow, and the shape of the combustion chamber on flame propagation. We conducted a 3D combustion simulation that, took into account various phenomena such spark ignition, flame propagation, and cooling loss. The values of the gas temperature and heat, transfer coefficient on the piston surface found from this 3D combustion simulation were input as the boundary conditions of a non-steady-state heat conduction analysis. The piston surface temperature, internal temperature and heat, flow were then calculated. It was found that the tendency of the calculated temperature distribution agreed with that of the temperature distribution measured by the hardness method.
