An analytical grain flow model for a combine harvester, Part I: Design of the model

A good understanding of the way grain kernels are processed and transported through a combine harvester is not so easy. Every section of the machine h as its own impact on the flow depending on geometrical dimensions and crop properties. Some work has already been performed on these individual machin e parts but this study, on the contrary, connects the different sections an d looks at their role in the total dynamic impact on the grain flow. Some different starting points are possible for constructing this flow mode l. In this work, an analytical approach is chosen in order to maintain the physical insight and the possibility of analysing the impact of parameter v ariations on the total dynamic influence. Another reason is the impossibili ty of measuring the incoming grain flow above the cutterbar of the machine which is necessary for 'black-box' identification. Simulations revealed tha t two parameters are dominating the process: the portion of the internal re turn flow of unthreshed ears in the total grain flow and the material speed across the grainpan of the machine. (C) 2001 Silsoe Research Institute.