Numerical and Experimental Characterization of Active Grille Shutter Loads for Automotive Applications 2022-37-0022

This work is developed in the framework of an industrial R&D project, titled ARIA (Active Responsive Intelligent Aerodynamics), having the main goal to improve the efficiency of a vehicle by introducing active aerodynamics supported by innovative actuation systems. The work focuses on the development of a new aesthetic Active Grille Shutter (AGS), which, differently from the currently marketed vehicles, does not include the presence of a grille in front of it. In addition, an innovative actuation system, based on the adoption of Shape Memory Alloys (SMA) is being investigated for the new AGS, with the main goal to exploit the advantages arising in terms of increased efficiency coupled with a marked weigh reduction. The proposed analysis aims, at first, at evaluating the effects of different AGS configurations on the drag coefficient, C_x, of the vehicle and on the related benefits. To this purpose, simulations of the whole vehicle are carried out to estimate the C_x in different AGS configurations and a simple AGS opening/closing strategy is adopted for the estimation of CO₂ reduction over a Worldwide harmonized Light vehicles Test Procedure (WLTP) cycle. Subsequently, for the design of the SMA-based actuation system, the estimation of the aerodynamic loads on the fins of the AGS and of the actuation forces is needed. Owing to the unavailability of experimental tests on the whole vehicle, an experimental/numerical study on the isolated component is carried out. A 1:1 model of the new aesthetic AGS is tested in a wind tunnel and data are used to validate a CFD model of the component. The aerodynamic loads on each fin of the AGS for different speeds are then computed and adopted in the numerical tool COMSOL Multiphysics for the design of the SMA based actuation system.