Wind tunnel tests on heavy road vehicles: Cross wind induced loads—Part 1

In the recent years, rollover has become an important safety issue for a large class of vehicles. Even though rollovers constitute a small percentage of all accidents, they have unproportionally large contribution to severe and fatal injuries. Under this point of view, rollover of heavy vehicles is particularly critical being associated with large traffic disruption, economic loss and risks connected to the transported goods. One of the main causes for heavy vehicles rollover is recognised to be cross wind. In order to determine which parameters (geometry and vehicle type, infrastructure scenario, turbulence conditions, etc.) most affect the aerodynamic loads acting on heavy vehicles, a comprehensive experimental campaign has been carried out in the Politecnico di Milano wind tunnel. The overall activity is presented in 2 papers. In this first paper attention is focused on a high-sided lorry in flat ground scenario. Mean aerodynamic forces and moments have been measured by means of a six-components dynamometric balance for different yaw angles and turbulence conditions. Moreover, in order to gain an insight of the flow pattern around the vehicle, pressure distribution on the vehicle surface has been measured. Finally, the vehicle aerodynamic admittance function has been assessed, for high turbulence conditions, to investigate the unsteady force/moment component. The second paper deals with the effect of infrastructure scenario (flat ground, embankment, double and single viaduct), of position (vehicle placed upwind or downwind) and of vehicle geometry/type (high-sided lorry with and without a trailed unit, tractor-semitrailer combination and tank truck) on the aerodynamic forces and moments, including both steady and unsteady components.

► Wind tunnel tests were performed on different heavy-road vehicles in different test conditions.
► Effects of scenario, vehicle and turbulence on force and pressure coefficients were studied.
► Effect of the vehicle geometry on the unsteady aerodynamic force component was analysed.