Using CFD in the Design of a Model Scale Radiator

Conference poster, 2007

During the last decade the drag coefficient of most passenger cars has dropped significantly to values around 0.3 and for certain models even below. A consequence of this is that the so called “cooling drag” constitutes a larger portion of the total drag coefficient, and one key problem in the minimization of the “cooling drag” is to optimize the cooling package. However, the situation is even more complex, since in this drag minimization model experiments are commonly used and the flow field in the model scale cooling package will be different as compared to the full scale. This effect must be taken into account in the total optimization process. Hence, the aim of the current work was to develop a realistic radiator geometry to be used in model scale wind tunnel experiments. In this work, the CFD code Fluent was used for studies of the scaling phenomenas by the use of a simplified radiator core geometry. Initial data available for the full size radiator geometry was an empiric expression for the pressure drop over the cooling package and in the computations the full scale radiator was modelled as a porous media in with its resistance described by an empirical equation. The results from the Fluent computations were used to design a model scale radiator, and to replicate the full scale cooling package a model radiator was manufactured out of honeycomb, for flow guidance, and fine wire meshes to obtain the relevant pressure drop. The set up was tested in a rig where the designed model was calibrated using different configurations of wire meshes. It was found in the test measurements that the outcome was a fully functional model scale radiator.