A Hybrid Wall Heat Transfer Model for IC Engine Simulations

The present work improves performance of the wall heat transfer model of Han and Reitz employing advanced turbulence modeling and formulating a compressible wall function in the framework of hybrid wall treatment. Some ambiguities related to the originally published model of Han and Reitz are discussed in order to provide a basis for the present modeling approach. A hybrid heat transfer model formulation relies on the k-ζ-f turbulence model which is capable of capturing turbulent stress anisotropy near wall and predicting heat transfer with more fidelity. The model is validated against spark ignition (SI) engine heat transfer measurements. Predicted wall heat flux evolutions on the cylinder head exhibit very good agreement with the experimental data, being superior to similar numerical predictions available in the published literature. In particular, extension of the flame-wall interaction effects, usually considered only in the first near-wall cell, to some of wall-adjacent cells, is found to be important for capturing evolution of the wall heat fluxes and improving model performance with respect to mesh sensitivity.