EVALUATION OF HEAVY-VEHICLE AERODYNAMIC DRAG

In an attempt to achieve a balance between Reynolds number, model scale, and tunnel blockage issues, a 1:3 scale heavy-vehicle testing program has been initiated at the Monash University 1.4-MW wind tunnel.

Significant progress has already been made in developing solutions that reduce the aerodynamic drag of heavy vehicles; however, there still remains plenty of work to be done to increase the uptake of these proven aerodynamic devices such as boat-tails, gap seals, and side skirts. Active flow control devices are immature and remain at a level where they are not being implemented in on-road situations.

A challenge to the uptake of drag-reduction devices on the road has been the lack of large-scale wind tunnel testing at representative Reynolds numbers. The majority of experimental development of heavy-vehicle aerodynamic technology has been completed at a scale of around 1:10, often on simplified bodies. At such a small scale, it becomes difficult to accurately represent detailed geometry, and very high wind speeds are required to replicate on-road conditions; this can push the power limits of many wind tunnels and lead to issues with compressibility.