Evaluation of the Thermofluid Performance of an Automotive Engine Cooling-Fan System Motor

Abstract

Experimental tests and computational fluid dynamics (CFD) simulations using the commercial code FLUENT were carried out to investigate the effects of the fan support hub geometry on the component heat transfer and cooling air flow through a simplified model of an electric motor for an automotive cooling-fan system, since little is known about the thermofluid dynamics of such machines. It has been found that the presence of radial ribs on the fan hub has a significant effect on drawing cooling air through the motor, particularly at lower air flowrates, regardless of the rotational speed. In addition, the rotational speed, hub diameter, fin height, and rib width are important parameters for inducing flow inside the hub while the tip gap and hub depth are not as influential. Increasing the number of ribs or fins has little impact on the performance of the hub. Good agreement was found between the experimental and predicted temperatures from heat transfer simulations of the motor for representative underhood environmental conditions. The present work shows that a valuable CFD tool can be developed to predict the temperature distribution inside the motor and offers a guide to the methodology whereby design modifications may be made to improve motor performance for a given application.