Investigation and Assessment of Factors Affecting the Underhood Cooling Air Flow Using CFD

Efficient thermal management of an engine cooling system and its surrounding components has been one of the most frequently visited topics in automotive industry. Especially, modern diesel truck engines have to deal with more heat rejection than ever to meet the rigorous emission and efficiency standards. As the maximum heat dissipated by a cooling system is limited to available inlet area to radiator, which is constrained by cab configuration, it is crucial to maximize the cooling airflow availability under given conditions. To be able to do so means to avoid additional development cost accompanying an altered cab configuration. At the same time, truck manufacturers have to deal with reduced product life cycles and develop reliable products economically. Fortunately, progress in simulation tools supported by the increasing computing power has also been in tandem with the ever-demanding environment in product development, helping to minimize the physical prototyping and tooling without compromising product performance. This paper presents the use of CFD (Computational Fluid Dynamics) as a simulation tool to investigate and assess various factors that affect the underhood cooling airflow. Specifically, the impact of the front end cooling module configuration (fan, fan shroud, heat exchangers) to cooling airflow and fan torque is closely examined. Suggestions for the best practice in modeling activities are also given for those interested in optimizing the underhood cooling airflow.