Effect of Cooling Airflow Intake Positioning on the Aerodynamics of a Simplified Battery Electric Road Vehicle

Abstract

<div class="section abstract"><div class="htmlview paragraph">The transition towards battery electric vehicles (BEVs) has increased the focus of vehicle manufacturers on energy efficiency. Ensuring adequate airflow through the heat exchanger is necessary to climatize the vehicle, at the cost of an increase in the aerodynamic drag. With lower cooling airflow requirements in BEVs during driving, the front air intakes could be made smaller and thus be placed with greater freedom. This paper explores the effects on exterior aerodynamics caused by securing a constant cooling airflow through intakes at various positions across the front of the vehicle. High-fidelity simulations were performed on a variation of the open-source AeroSUV model that is more representative of a BEV configuration. To focus on the exterior aerodynamic changes, and under the assumption that the cooling requirements would remain the same for a given driving condition, a constant mass flow boundary condition was defined at the cooling airflow inlets and outlets. A parametric study was conducted by spatially moving the cooling intakes, with constant total area, across the front of the vehicle. Power consumption of the fan had to be considered when maintaining the desired airflow rate through intakes without sufficient ram air. As expected, moving intakes away from the stagnation region increased drag. Lateral outward movements altered the flow fields around the front wheels, while vertical movements of the intake only showed marginal flow changes across the top and bottom halves of the vehicle. The flow characteristics towards the rear were unaffected, and the changes observed were mostly local. Including power requirements of the fan, increments up to 15% of total vehicle drag were observed.</div></div>