Search Results

Aerodynamic measurements in automotive wind tunnels are degraded by test section interference effects, which increase with increasing vehicle blockage ratio. The current popularity of large vehicles (i.e. trucks and sport utility vehicles) makes this a significant issue. This paper describes the results of an experimental investigation carried out in support of the Ford/Sverdrup Driveability Test Facility (DTF), which includes an aero-acoustic wind tunnel (Wind Tunnel No. 8). The objective was to quantify the aerodynamic interference associated with two candidate test section configurations for Wind Tunnel No. 8-semi-open jet and slotted wall. The experiments were carried out at 1/11-scale in Sverdrup laboratories. Four automobile shapes (MIRA models) and six Sport Utility Vehicle (SUV) shapes representing blockages from 7% to 25% were used to evaluate changes in measured aerodynamic coefficients for the two test section configurations.

The front-end design process in the automotive industry today is time consuming and expensive. Although CFD (Computational Fluid Dynamics) modeling is helpful, many vehicle development tests in different wind tunnels are still required to balance the competing requirements of power train cooling, vehicle aerodynamics, climate control, styling, body structure, and product cost. For example, engine cooling and climate control heat exchangers require adequate airflow to achieve their performance. But, this airflow increases cooling drag and can compromise vehicle handling. Internal air deflectors (ducting) are often used to make the frontal opening more efficient and help prevent heat recirculation from the hot engine compartment to the A/C condenser at idle. But this increases product cost and can compromise underhood temperature. A more efficient and faster process is needed to support these trade-off discussions.