Improving aero-thermal environment in vehicle under-hood through small modification upstream the cooling module

Abstract

The control of vehicle cooling airflow is one of the key issues of under-hood thermal management as well as the reduction of cooling drag. Aerodynamic analysis using full vehicle CFD method was conducted to further improve the cooling efficiency of a production vehicle equipped with an air-guide. Existing under-hood airflow problem of the original vehicle was first analyzed, and then several modified schemes using various deflectors in the area between the front bumper and the condenser were proposed. The comparison of the under-hood airflow characteristics of each modified scheme and the original model was carried out. The simulation results revealed that sealing the cavity between the front bumper and the anti-collision beam could improve the airflow rate through the cooling module with a reduction in the total air intake volume from the grilles, while blocking the channel from the upper grille opening to the cavity could increase the airflow evenness through the cooling module. The aerodynamic and thermal tests in wind tunnels demonstrated that, for the best scheme with three deflectors at 40 km/h, the temperature of the coolant and the exhaust pipe were reduced by 6.6°C and 15°C, respectively, with a minor reduction in Cd,grilleopen, compared to those of the original vehicle. With less cooling airflow rate, the scheme with a single deflector blocking the upper channel of the cavity achieved similar cooling effect as the best scheme, the reductions of the coolant temperature and the exhaust temperature at 40 km/h were around 6.6°C and 13°C, respectively, with a similar value of Cd,grilleopen, compared to those of the original vehicle.