Abstract
Numerous aerodynamic designs of high-speed coaches have been made to reduce aerodynamic drag
for lower fuel consumption and to keep the driving stability of the vehicle on a highway. However, the external body shape of a long-distance, high-speed coach manufactured around the world is in a rectangular shaped blunt body. With this conventional body configuration of the bus, it is not easy to have an optimum shape of the bus with the minimum aerodynamic drag. From the previous study, it was found that total aerodynamic drag on a running vehicle is comprised of around 70% in pressure drag by stagnation on the front-side of the vehicle and 30% in induced drag by vortex at the rear-side of it. In this study, a streamlined design concept was incorporated to the front-side of a long-distance model bus to see its effect on the reduction in aerodynamic pressure drag and a general type of RGV (rear guide vane) was applied to see its effect on the reduction in the induced drag at the rear flow field of the model bus. Computational fluid dynamics (CFD) method was incorporated to analyze the variation of aerodynamic effect on the model buses with the change of body configuration.
From the study, it was found that 27.4% of the total drag of the original bus (Model-0) was reduced on the model-3 that is equivalent to 17.3kW of an engine brake power at 120km/h in speed. The annual economical effect is the reductions in about 14,610 liters of fuel and 41.2 tons of CO2 per year by each car at the assumed operating condition.
