Experimental Research on Flow around a Cooling Fan Unit in a Engine Compartment Model of Construction Machinery

To study the effects of cooling fan unit geometries on cooling performances in a construction machinery, an experimental model is built. The airflow rates, velocity vectors around the fan, pressure differences between front and aft sides of the cooling fan unit, and required power of the motor that drives the fan are measured. Three-dimensional velocity fields are measured by a hot-wire anemometer. Geometric parameters investigated are (1) ratio of the shrouded axial chord to the axial chord of the fan and (2) distance between the radiator and fan. The fan transit from the axial flow mode to the centrifugal flow mode and vice versa, when the resistance of flow passage is changed. The maximum airflow rate and highest efficiency are obtained when the fan is covered by the shroud by 50% of its axial chord length. Both the airflow rate and efficiency increase as the distance between the radiator and fan increases.