The paper presents the development of a proposed rear powertrain cooling system of a minivan. The packaging of cooling system is finalized such that the radiator faces towards the rear of the vehicle bumper which is opposite to the conventional rear cooling system (i.e. radiator faces towards the front of the vehicle).
In the small minivan, the space ahead of the engine is used as a floor for passenger foot. Due to these space constraints, the cooling system has no choice, but to move rear of the vehicle and above the departure plane to meet packaging requirements. Furthermore, in the conventional rear cooling system, in front of the radiator, there is engine and exhaust system, which heats up the air going to the radiator and reduces radiator cooling performance. Thus the cooling system is placed such that the radiator faces the rear bumper to draw in cooler air. In this condition we don’t depend on the ram air but on the fan to meet required airflow.
1D simulation using LMS-Amesim and CFD tools FLUENT are used for conceptual study. Comparison study on air flow, cooling performance and under-hood temperature is done by testing on a mule vehicle. Grill opening, departure angle, critical components heights and surrounding body panels for underbody are considered in packaging of the vehicle.
The air flow, ROA of Coolant and ROA of Oil are measured for two conditions, i.e. radiator facing towards rear bumper and radiator facing towards powertrain. It is observed that the effect of rear vortex has negligible impact on the airflow provided by the fan, for vehicle speed less than 65kmph.