Wittmeier, F. and Kuthada, T., "Open Grille DrivAer Model - First Results," SAE Int. J. Passeng. Cars - Mech. Syst. 8(1):252-260, 2015, doi:10.4271/2015-01-1553.
Cooling air flow is an important factor when it comes to vehicle performance and operating safety. In addition, it is closely linked to vehicle aerodynamics. In recent years more and more effort is being spent to optimize the losses generated by the flow through the vehicle. Grille shutters, better sealing and ducting are only some examples for innovations in this field of work, resulting in a lower contribution of the cooling air flow to overall drag.When investigating those effects, both experiments and numerical simulations are commonly used in the automotive environment. Still, when comparing the results from both methods, differences in the effect of cooling air flow can often be observed.To better understand the effects of cooling air flow, the ECARA Subgroup CFD decided to establish a common design for a generic open source vehicle model with a detailed underhood compartment to lay the foundation for a common investigation model. The DrivAer-model, developed at the TU Munich, was chosen as the baseline vehicle, due to its high level of detail and the good acceptance in the community in recent years.Based on the input of the members of the group, FKFS designed a baseline version of the underhood compartment including a radiator package with fan and a representation of the engine in close cooperation with TU Munich. Since the majority of DrivAer models built are for scale model testing, the engine features a simplified design to be used as a starting point for CFD validation. This simplified design fits well to the level of detail of the original model. The underhood flow can both exit through defined openings in the front wheel houses and into the underfloor region, which allows different cooling air concepts to be investigated. The cooling air package is based on component data of a mid-size passenger car.This paper gives some insight into the model and presents first results from both CFD and wind tunnel measurements in quarter scale including rotating wheels and state-of-the-art ground simulation.