Underhood thermal management: Temperature and heat flux measurements and physical analysis

Aerodynamic cooling drag, caused by car underhood cooling, can be reduced by better underhood aerothermal management. This study addresses the aerothermal phenomena encountered in the vehicle underhood compartment by physical analysis of the heat transfer modes in complex internal flows. We report here underhood heat flux and temperature measurements on a vehicle in wind tunnel S4 of Saint-Cyr-France using a new experimental method. The underhood is instrumented by 40 surface and air thermocouples and 20 fluxmeters. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. The ultimate aim is to reengineer the underhood architecture so as to reduce the cooling air flow rate in the underhood component and hence the aerothermal cooling drag.