Aerodynamic Characteristics and Flow Visualization of Motorcycles

Abstract

Motorcycles are more lightweight than cars, unstable because of two wheels, and tends to be influenced by oncoming flow. In this experiment, the aerodynamic characteristics of two 1/5-scale naked motorcycle models are measured using a low-speed wind tunnel and a six component force balance. The models are basically same, but one has the cowling and the other doesn't. The wake is visualizied using wake survey, and the effect of the cowling is investigated from the view points of the C_D value and the wake structure. It was obtained that the model equipped with the cowling has a lower C_D than the model without the cowling. The results of the wake survey show that there is small turbulence and the generation of vortices is surpressed in the former case. It is concluded that the cowling is effective to arrange the flow and decrease the aerodynamic drag.