Modeling and simulation of grain threshing and separation in axial threshing units Part II. Application to tangential feeding

The threshing process - by which the grains are removed from the ears - begins effectively at the feeding zone of threshing unit. At the same time, grain separation occurs in the feeding zone of the threshing unit if the rotor cage has openings. This paper presents the application of mathematical model for grain threshing and separation (described in Part I) in an axial threshing unit with separation beginning in the tangential feeding zone. The model describes and quantifies the cumulative percentages of unthreshed grain, free grain, and separated grain over the entire length of the rotor. Grain threshing and separation losses are also quantified. The mathematical model was validated using reliable and comprehensive experimental data. Very good agreement was found between theoretical (predicted) and experimental data for separated grain as well as for threshing, and separation losses of grain over the entire range of testing conditions. Assuming that a set of minimum experimental data is provided for initialization of model parameters, the model can be further used for: - process simulation that means reduction of testing time and associated costs, - optimization of design and functional parameters of threshing unit, - development of control software and process controllers for combine harvesters. This is the only model ever published for this type of axial threshing units.