A Multidimensional Model Prediction of Heat Transfer in Non-Fired Engines

An axisymmetric three-dimensional model for in-cylinder processes has been applied to the predictions of wall heat transfer in a non-fired engine cylinder. Computed heat fluxes are shown for combustion chambers with a flat piston and a deep-bowl piston for swirl and no-swirl cases. The predictions compare well with existing experimental heat fluxes at several different radii on a cylinder head except in a central part. It is also shown that the predictions of surface-averaged heat flux are consistent with those obtained from empirical correlations. The effect of compression-expansion work is indicated by predicted temperature profiles and typically demonstrated by phase difference between the heat flux and the bulk-mean gas temperature. Computational discussions are given on local heat fluxes in the deep-bowl-piston combustion chamber and suggest that local heat fluxes are greatly increased by squish motion, squish-induced vortex, and swirling motion spun-up in the bowl.