An Analysis of 3D Simulation of SI Combustion with an Improved Version of the Kiva 3V Code: Numerical Formulation and Experimental Validation

The correct simulation of combustion process allows to better face several SI engines design problems, not only for innovative mixture formation concepts (stratified or ultra-lean charge), but for traditional homogeneous mixture as well. Even though many commercial codes are able to describe the complex 3-D non reacting fluid dynamics in ICE, the simulation of high turbulent flame propagation does not seem to be a completely solved problem yet. In this work a comparison between two different turbulent combustion models (a characteristic time based one by Abraham and Reitz [2, 15, 16] and a flamelet based one by Cant and AbuOrf [4, 20]) has been performed using KIVA-3V code to assess simulation reliability. Models predictive capabilities have been tested with reference to specific data acquired at the engine test bench of Tor Vergata Mechanical Engineering Department on a Fiat Punto 1242 cc 8 valves SI engine over a wide range of operating conditions. A generally good agreement has been observed between experimental and numerical results obtained by using both the combustion models. In addition it can be noticed that, thanks to a more physical description of the local turbulent flame characteristics, Cant model seems to exhibit more predicting reliability in the whole engine operating field.