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A Quasi-Dimensional Model Applied to 4-Valves-Per-Cylinder Combustion in SI Engines
Published April 28, 1998 by Institution of Mechanical Engineers in United Kingdom
This paper describes the experimental and theoretical investigations of combustion model parameters affected by squish-generated turbulence. Analysis of cylinder pressure-cr records allowed calculation of the burned gas velocity. The results of turbulent to laminar flame speed ratio showed a double peak characteristic of four-valve-per-cylinder, S.I. engines with squish regions.
A quasi-dimensional, multi-zone combustion predictive model was extended to include the effect of squish flow at full load operating condition and over a wide range of engine speeds. The model offers a convenient method to explore, for a 4-valve, petrol S.I. engine the effects on thermal efficiency, gas temperatures and other variables of different combustion chamber geometry and engine geometry including crank-connecting rod ratio, cylinder capacity and stroke/bore ratio.