AEROACOUSTIC INTERACTION EFFECTS BETWEEN PARALLEL LOW-PRESSURE AXIAL FLOW FANS

Paper in proceeding, 2023

Engineering applications involving multi-fan arrangements in close proximity face challenges including sound wave interference and inlet flow interactions. The former leading to beating effects and the latter to non-ideal inlet conditions, potentially affecting the aerodynamic and acoustic performance of the system. The herein study investigates the above within the application space of automotive cooling fans. Two identical low-pressure axial flow cooling fans, with rotating rings, were installed in parallel. Different inlet shroud lengths and spacing between the two fans' rotating centers were tested. Acoustic measurements were performed in a bespoke fan test rig, leading to sound power estimation along with acoustic beating investigation. Complementary velocity measurements upstream of the fan were performed using laser Doppler anemometry. This led to the identification of possible inlet flow interactions and upstream disturbances which match the acoustic spectra. Moreover, a single fan arrangement was documented as means of reference for the parallel fan system.