Cooling Module Performance Investigation by Means of Underhood Simulation

In this paper a study of different front end and cooling module designs on the engine cooling performance by means of simulation tools is presented. Various configurations of grille and front end intake geometries of a BMW 5 series passenger car are investigated at different operating points concerning mass flow and mass flow distribution on engine cooling components. Different cooling module configurations were studied concerning the position of an additional motor oil cooler. The simulations were done with 1D Behr Integrated System Simulations Software (BISS) as well as the commercial 3D Navier-Stokes solvers UH3D and Star-CD. BISS and CFD software are coupled by passing the results as boundary conditions enabling to use the full potential of both 1D and 3D modeling. Differences between UH3D and Star-CD modeling assumptions are discussed and advantages and disadvantages concerning accuracy and turnaround time are quantified.

To validate the simulation methods used, the simulation results are firstly compared for the cooling module including cooling components and fan with measurement data. Therefore Micro Probe measurements on the Behr module test rig were done to give a spatial resolution for velocity distribution and pressure. Secondly measurements from the Behr engine cooling wind tunnel are opposed to the full vehicle underhood simulation results.