RELEVANCE OF RADIATOR INSTALLATION ON THE EFFICACY OF NOISE REDUCTION STRATEGIES IN AN INDUSTRIAL ENGINE COOLING FAN

Engine cooling fans must be efficient and quieter, as their acoustic contribution is today more noticeable considering the reduced noise from electric motors. Therefore, more effective noise reduction technologies must be designed. This paper investigates how noise reduction technologies, designed for an isolated fan, are impacted by the presence of a radiator pulling upstream. Two modifications to the baseline fan geometry are studied: (i) one with a ring shape that mitigates the backflow-rotor interaction and (ii) one with stator vane azimuthal spacing optimized to reduce rotor-stator interaction tonal noise. They are assessed with high-fidelity simulations performed both on an isolated fan and a full cooling module including the radiator, which is simulated using an equivalent porous medium. Results reveal that the modified ring shape effectively prevents backflow-rotor interaction on the isolated fan, reducing broadband noise by radially redirecting the backflow. However, its performance is less effective when a radiator is present due to the presence of the casing. Conversely, stator vane optimized spacing shows robust noise reduction in both configurations, because the effect of distributing tonal energy across several modes is not altered by the presence of the radiator.