CFD Application in Automotive Front-End Design 2006-01-0337

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.

The objective of this report is to examine the suitability of using one CFD model to address this need. One front-end CFD model is used for all three attributes: power train cooling, thermal re-circulation at idle and cooling drag. The focus is on SUV and Pickup Trucks with mechanical fans. The following parameters are investigated: fan speed, engine heat rejection, and air deflector (air ducting) impact on recirculation. Overall, the CFD quantitative results look very reasonable and offer the promise of improving the product development process. The qualitative flow field and temperature contour maps were very helpful to the understanding of the results.