Design Considerations for Maximizing Cooling Package Performance

Abstract

More stringent heavy vehicle emissions legislation demands considerably higher performance out of engine cooling systems. Presented is a study of various design parameters that can be used to maximize the cooling airflow for a Freightliner Class 8 truck. CFD analysis was used to analyze various fan shroud profiles, different fan immersions (overlap between the fan and fan shroud) and with two different engines. All of these design parameters lead to significantly different flow behavior inside the fan shroud and in the underhood region, in turn creating adverse or favorable pressure gradients. A series of isothermal CFD simulations are used to determine the effects of these flow characteristics on the radiator mass flow. For one of the simulation setup the predicted radiator coolant inlet temperature is compared to measured physical test data at different fan speeds. The methodology for the optimization of the cooling performance is outlined. It is shown that the presented simulation approach can provide accurate predictions of cooling airflow and coolant temperature.