Aerodynamic Analysis of Low-Pressure Axial Fans Installed in Parallel

Abstract

Ducted rotor-only low-pressure axial fans play an integral role in automotive thermal management. The tightly packed under-hood region and downstream heat-exchanger shape limit the fan diameter. In order to circumvent this limitation, multiple cooling fans of small diameters are tightly packaged and placed in parallel. Currently, there is limited scientific work, which study the aerodynamics of low-pressure axial fans when installed in parallel. This work aims to quantify the aerodynamic performance and the flow-field as a result of installing low-pressure axial fans in parallel through Computational Fluid Dynamics (CFD). Publicly available experimental data from Friedrich-Alexander University, is used for the validation of the numerical setup. Three-dimensional, full-annulus, Unsteady Reynolds-Averaged Navier Stokes (URANS) analysis has been performed for both a single-fan and two-fans installed in parallel and their respective aerodynamic performance has been compared for the operation condition identified as the best efficiency point in experiments. Only small-differences are observed in the overall aerodynamic performance of the two-fans in parallel compared to a single-fan. A circumferential non-uniformity in the form of a local high-pressure zone at the inlet of the fan is observed, when the two-fans are placed in parallel. The resulting circumferential non-uniformity is quantified, both in space and time. A strong correlation is found between the pressure fields of the two-fans installed in parallel.