Host: The Japan Society of Mechanical Engineers
Name : Mechanical Engineering Congress,Japan
Date : September 11, 2016 - September 14, 2016
This research deals with improvements of side-wind stability about restraint of yawing and turning sideways under high speed operation of cars. For this purpose a side-jet machinery called aero slit is adopted, which decreases the yawing moment by causing separation in the case of receiving side wind. The Ahmed body is used as a simplified car model with an aero slit on one side. In the slit size the width is 8mm common, the height has three patterns (20 mm, 30 mm, and 40 mm), and the slit position has five patterns (0mm, 25mm, 50 mm, 100 mm, and 150 mm) from the front end of the model. Totally sixteen patterns are manufactured together with a bumper without an aero slit. In the experiments, the wind speed is taken as 20 m/s with yawing angle changing every 10° from 0° up to 60°. As results of yawing, the maximum value of yawing moment was decreased at yawing angle of about 30° by most of slits. The most effective slit is 20 mm in height at 50 mm in position, i.e., smallest height at ending location of edge rounding. Next, the wind speed at overturning limit is estimated by the evaluation method with the overturning moment using lift and side force. Consequently, an overturn of cars with an aero slit can be restrained in angle 0° to 20° and 60°, but slightly in angle 20° to 50°. Thus the effect of the aero slit has been confirmed on yawing and turning sideways.
