CONICET | Buscador de Institutos y Recursos Humanos

This work presents the first stage of a broader experimental and numerical study of the heatflux through the walls of an internal combustion engine running under low carbon footprint alternativefuels. Heat losses during engine operation have a significant impact on engine emissions, efficiency,and thermal stresses. As an initial validation step, the work at hand deals with the applicability ofmodels for predicting the heat flux magnitude of the end gas flow in proximity to the combustionchamber walls. Measurements of pressure dynamics in the engine manifolds and cylinder, and of theheat flux in the cylinder walls, by means of a differential thermocouple-type heat flux sensor, are usedfor validating the computational model, in cold flow conditions. As heat flux is strongly affected bythe complex flow structures induced by the different engine components, the complete fluid domain ofthe engine was included in the computational domain, making the atmospheric boundary conditions atthe inlet and exhaust manifolds the overall system boundaries. Therefore, the in-cylinder flowdynamics are exclusively dependent on the valves and piston kinematics. The computational modelcombines a pseudo-supermesh approach with dynamic layering, coupled with a valve opening/closuremodel. This enables the model to be efficient, in terms of computational cost, robust and versatile forparallel computation. These are crucial features when dealing with complex simulations. The accuracyof the different models was evaluated comparing the heat flux evolution throughout the compressionand expansion cycles of a closed piston-cylinder assembly and by computing a series of quantitativeindicators. It was found that, while the in-cylinder pressure calculation converges rapidly, heat-fluxconvergence requires larger computational times.