Effect of Front Window Angle on The Automobile Dynamic Performances

The paper simulates the 3-dimentional airflow around automobiles with front window angles of 20deg, 30deg and 45deg to investigate the influence of the flow structure on the drag. The free space outside the automobile is created with 3-times automobile length upstream and downstream, 2-times automobile height and width. The scale of automobile is 435 mmtimes168 mmtimes148 mmtimeslengthtimeswidthtimesheight. The coefficients of flow resistance and of uprising force are defined. Analyzing the result, it can be concluded as follows: The optimal front window angle is 30deg, because the coefficients of flow resistance is lowest among three front window angles in the study ,and the coefficient of uprising force is not very high. The coefficient of flow resistance decreases with increasing the moving velocities, and does not decrease with increasing the front window angles.