Mohammad hasan Shojaeefard - Professor –Iran University of Science and Technology
Alireza Noorpoor - Assistant Professor –Iran University of Science and Technology
Mehdi Sadegh kazemi - Post graduate student-Automotive Department - Iran University of Science and Technology

As turbulence has a significant effect on combustion, affecting ignition delay, combustion duration and emission level, the effects of valve lift profile variations on in-cylinder turbulence are investigated in this study. Volumetric efficiency is also studied as a determining factor on engine break power. The influence of five different cases i.e. fast lift, slow lift, sinus lift, flat lift and diminished flat lift are analyzed. The engine is a turbocharged heavy duty diesel engine with about 10 liter per cylinder swept volume. The aim of the research is to improve the performance of the engine, which is under studying. The mesh generation and CFD calculation are accomplished using ICEM-CFD package and KIVA-3V code. To keep a perfect match between engine geometry and KIVA-3V, some modifications are made on the code. Also, to trust the reliability of the results, the grid independency and validation are accomplished using different grids and experimental data. The results revealed that the valve lift profile variation has a profound effect on in-cylinder turbulence but a slight effect on volumetric efficiency. Also volumetric efficiency and in-cylinder turbulence do not show the same trend to the valve lift profile variation.