Using the 3D engine model a tumble control valve was installed in the intake port to provide a means for controlling the engine airflow motion. Based on a CFD software

the evolution and development of the cylinder flow field with the change of crank angle were calculated

the tumble motion and turbulent kinetic energy were assessed

the spray atomization process and mixture concentration distribution were simulated under the condition of equivalent air/fuel ratio

and the combustion process was analyzed. Results show that use of tumble control valve can effectively improve the cylinder tumble ratio

and enhance the turbulent kinetic energy

allowing to improve the combustion rate and combustion process at the condition of 0.2MPa at 2000r/min and full load at 1750r/min. Moreover

a special design of piston top shape was used to prevent the spray wall impingements. These improvements make the simulated cylinder combustion pressure curves and the actual engine bench test results have a good consistency.