Application of Design of Experiments and Physics Based Approach in the Development of Aero Shutter Control Algorithm

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. Number of runs needed is reduced by several orders of magnitude while ensuring the accuracy of the model. Physics based approach to reduce the number of runs to minimal is also demonstrated. This approach works on the hypothesis that at given normalized flow, resistance of the grille is constant irrespective of vehicle speed or fan state [ 1 ]. Results from DOE study, physics based approach are validated with actual simulations at some points. Relative merits of these approaches are concluded.