NUMERICAL INVESTIGATION OF AN AUTOMOTIVE AXIAL FAN: A COMPARISON AMONG DIFFERENT CFD SOFTWARE PACKAGES AND EXPERIMENTAL VALIDATION

Electrical and fossil fuel powered vehicles require to reject some form of heat produced as a byproduct of their operating principle. This task is performed by radiators, typically equipped with axial flow fans to maximize the specific processed flow rate. These fans, as well as all the other fans that typically equip the vehicles (e.g., for HVAC purposes), are required to be very efficient and to produce a minimum level of noise. In this framework it is of crucial importance to adopt all the tools that can help in understanding the source of inefficiency and noise. This work presents the adoption of Computational Fluid Dynamics (CFD) as a possible tool for the investigation of the fluid dynamics of an axial flow fan. In order to let CFD become routinely employed, a sequence of validation steps is required by industries. In this work, two different CFD tools (ANSYS-CFX and OpenFOAM-v2006) are employed and the results of the investigation are compared to experimental data for assessing the reliability and the accuracy of each of these tools. Experimental data are obtained with two test benches: one build in compliance with ANSI/AMCA standards for airflow performance evaluation and one ad hoc developed for PIV measurements (i.e. flow field visualization). The capability of the CFD softwares of correctly replicating the fan performance and flow field even in this complex set-up (due to the loose constraints of the fluid flow) is shown both with steady and transient simulations.