Effect of a cross-flow opening on the performance of a centrifugal fan in a combine harvester: Computational and experimental study

In modern harvesting machines, one of the critical factors to fulfil the current demand of capacity and output under a wide range of field and crop conditions is the capacity of the cleaning fan. In order to obtain an effective cleaning action, the fan has to generate a forceful and even air flow over and through the complete width of sieves. This paper presents the effect of a cross-flow opening on the distribution of flow along the width of a forward curved, wide centrifugal fan with two parallel outlets. Computational Fluid Dynamics (CFD) is utilized to study the effect of the addition of a cross-flow opening on the performance of the fan using three fans of similar geometries but different in their cross-flow opening. Velocity profiles at the outlets of one of the fans are measured using X-wire hot-wire anemometers and they are used to validate the CFD simulations. Loads on the fan are created by using perforated plates whose resistance curves have been determined in a wind tunnel. It is found out that addition of the cross-flow opening throughout the whole width of the fan plays a crucial role in having uniform air flow along the width of the outlets of the fan. Comparisons between the simulations and measurements generally show good agreement.