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This paper deals with the numerical investigation of the in-cylinder flow structures under steady-state conditions utilizing the finite-volume CFD package, STAR CCM+. Two turbulence models were used to simulate the turbulent flow structure namely, Realizable k-ε and Reynolds Stress Turbulence Model, RSTM. Three mesh densities of polyhedral type are examined. The three-dimensional numerical investigation has been conducted on an engine head of a pent-roof type (Lotus) for a number of fixed valve lifts (2mm, 5mm, 8mm) at two pressure drops 2451.662 Pa and 6227.222 Pa that is equivalent to engine speeds of 2500 and 4000 RPM respectively. This correlation between pressure drop and engine speed is provided by Lotus engineering according to real engine studies. Based on the comparison between two turbulence models, the turbulent flow structure was simulated using RSTM model for a number of tumble and swirl planes.

This paper deals with experimental investigations of the in-cylinder flow structures under steady state conditions utilizing Particle Image Velocimetry (PIV). The experiments have been conducted on an engine head of a pent-roof type (Lotus) for a number of fixed valve lifts and different inlet valve configurations at two pressure drops, 250mm and 635mm of H2O that correlate with engine speeds of 2500 and 4000 RPM respectively. From the two-dimensional in-cylinder flow measurements, a tumble flow analysis is carried out for six planes parallel to the cylinder axis. In addition, a swirl flow analysis is carried out for one horizontal plane perpendicular to the cylinder axis at half bore downstream from the cylinder head (44mm). The results show the advantage of using the planar technique (PIV) for investigating the complete flow structures developed inside the cylinder.