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This paper outlines a process to assess the aerodynamic performance of different vehicle exterior surfaces. The initial section of the paper summarizes the details of white-light scanning process that maps entire vehicle to points in Cartesian co-ordinate system which is followed by the conversion of scanned points to theme surface. The concept of point-cloud modeling is employed to generate a smooth theme surface from scanned points. Theme surfaces thus developed are stitched to under-body/under-hood (UB/UH) parts of the base vehicle and the numerical simulations were carried out to understand the aerodynamic efficiency of the surfaces generated. Specifics of surface/volume mesh generated, boundary conditions imposed and numerical scheme employed are discussed in detail. Flow field over vehicle exterior is thoroughly analyzed. A comparison study highlighting the effect of front grilles in unblocked condition along with air-dam on flow field has been provided.

Aero shutter is device used for controlling air flow through front grille of the vehicle for optimal thermal and energy management. Conventionally shutters were controlled by reactive algorithm - that actuate based on reaction to powertrain cooling system response like engine coolant temperature. The predictive algorithm of aero shutter proactively actuates engine cooling fans and shutter to different positions to meet real time cooling requirement. This algorithm needs map of shutter position required for a given air flow requirement which is function of vehicle speed, fan speed, opening of another shutter (if dual shutters are used on two grilles). Deriving such map requires enormous number of simulations or wind tunnel tests at each of these parameter combinations. This paper presents Design of Experiments (DOE) studies using statistical approach to have minimal number of runs to develop such map.