Effects of a Moving Surface Boundary Layer Control Device (MSBC) on the Drag Reduction in Heavy Commercial Vehicles

Rapid escalation in fuel prices has motivated the manufacturers of heavy commercial vehicles to focus their attention towards efficient aerodynamic design of surface transport systems such as trucks–trailers, railways etc. In order to reduce the drag force acting on truck–trailer assemblies, the flow separation phenomena, occurring on the roof of the trailers, need to be controlled. A number of add-on devices have been developed for this purpose by different investigators but most of these devices are still not being used for several reasons including difficult integration with the structure and non-optimal configuration. In the present study, based on the theory of moving surface boundary layer control, a novel fuel saving device has been developed, and its operation optimised, in order to control the flow separation. Computational Fluid Dynamics (CFD) based techniques have been employed to analyse the aerodynamic performance of a truck–trailer assembly, integrated with a moving surface boundary layer control device (MSBC). The device has been shown to be very effective in reducing the flow drag force being imparted on the truck – trailer assembly, and hence reducing the fuel consumption. Operation of MSBC device has been optimised to obtain a range of rotational speeds of the device over which it provides maximum reduction in aerodynamic drag.