Analysis of Different Types of Wind Tunnel's Ground Configuration Using Numerical Simulation 2010-36-0078

The work here presented aims to study different types of ground configurations, located at the test section of a wind tunnel and to check their influence on the drag coefficient of one car, using only computer simulations. The drag coefficient of a vehicle is one of the most important aerodynamic proprieties, and as low as this drag value can be, the car performance will increase and the fuel consumption will decrease, item which has been pursued in new vehicles. Starting from one real wind tunnel test of a small pickup, with static test section ground, a virtual model was built and tested using CFD, following the same configuration of the real test. The difference between test and simulation results was 0.25%, showing that the methodology here used is reliable. After that, two other types of ground were simulated: elevated plate and moving belt and the results show that drag value decreased 0.002 and 0.012 respectively, compared to the value obtained with static ground simulation. The flow behavior is demonstrated with colored images of the velocity and the pressure fields. As a complement for this work, two other cases were studied: the first one analyzed one isolated wheel in two different types of ground: static and moving belt, at the same wind tunnel test section, aiming to measure the influence of these types of ground, without the need of using a complete car, saving computational and modeling time. The second study shows the influence of mesh size, considering three cases: 5, 10 and 20 mm, in order to evaluate the influence of it on the drag coefficient results provided by CFD.