The yearly wheat production in the EU is over 150 million tons. This is only possible thanks to efficient machinery, such as the combine harvester. This agricultural machine does not only harvest the wheat, but also cleans it by separating the straw and chaff from the useful grain on site, as such limiting transportation. The left-over chaff and straw is redistributed over the field. The same machine is used to harvest crops like barley, corn, canola and more. This thesis focusses on the cleaning system, which separates the grains and the chaff, making using of high velocity air flows and moving sieves. In the combines of CNHI, the air flow is generated using a cross-flow fan.
The CNHIndustrial branch in Zedelgem specializes in developing and manufacturing combine harvesters, among other agricultural machines. Within CNHI, Zedelgem is recognized as a center of excellence for product design.
Figure 1 New Holland Combine Harvester
Figure 2 Simulation of cleaning process with cross-flow fan
The aim of this master thesis is to investigate how the sieves and the airflow from the cross-flow fan affect the removal of the chaff from the grain, in order to limit as much as possible the amount of grain that is expelled from the machine together with the chaffs. As such food waste is avoided. Moreover, improving the efficiency of the cleaning process may allow reducing the power consumption of the cross-flow fan.
This process is a complex interaction between crop and air and will be investigated by performing a particle simulation in OpenFoam. You will gradually build up a model for the cleaning process by stepwise adding more complexity. Including the motion of the cleaning system will require the dynamic or overset meshes. The crop loss is reduced by for example modifying the geometry or optimizing the sieves.
In this thesis you will: