Construction of a mathematical model of the indicator of grain loss after the thresher of a grain harvester
Authors:   SSI «L.Pohorilyi UkrNDIPVT», Halin S. , Zanko M. , Haidai T. , Stepchenko S. , Len O. ,   SSI «L.Pohorilyi UkrNDIPVT»
Published: February 2024

The purpose of the research: to develop a multifactorial mathematical model of the indicator of grain loss behind the thresher of a drum-type grain harvester, taking into account the connection and dependence between the elements of different groups of factors that characterize the thresher as a system. Methods and materials. The application of the analysis method makes it possible to single out its structural and functional systems within the thresher, in particular - the complex threshing and separation system (CTSS) of the thresher and explore it taking into account technical parameters, technological modes and operating conditions independently of other systems. According to the synthesis method, the indicator of grain losses was experimentally investigated under the condition of complete unity and interconnection of the technical and technological systems of the thresher. The determination of grain loss by the combine thresher in different conditions of grain and straw moisture, with different modes of supplying the technological mass to threshing was implemented experimentally in real economic conditions. The development of a mathematical model of the grain loss indicator was carried out using mathematical modeling methods. The results. To establish the connection and dependence of the grain loss indicator Δq on the factors to which the technical parameters, technological modes and working conditions are assigned, a graphic model of the thresher was used at the level of these indicators and factors influencing them. As a determining system, in accordance with the technological role in the formation of the level of losses Δq (%), the parameters of the complex threshing-separating system are adopted. The total loss of grain in different modes of supplying the bread mass to the threshing machine is taken as an evaluation indicator of the quality of the threshing machine. The moisture content of the straw and the weight ratio of grain and straw - strawness - are also accepted as factors of influence. A multifactorial experiment was conducted to determine the loss of grain by threshers of drum-type grain harvesters of different productivity. The analysis of the obtained experimental data shows: 1) the thresher, the technical parameters of which are aimed at ensuring greater throughput, reacts to a lesser extent to “difficult” working conditions, which are characterized by high straw moisture (up to 30%) and strawness (up to 1.60). This is manifested in its ability to work with grain losses of less than 1.5% and high feeding modes - a throughput of 12-14 kg/s; 2) straw moisture and its amount (strawness) determine the influence on the quality of the thresher’s functioning: an increase (decrease) in straw moisture (or strawness) causes a corresponding increase (decrease) in grain losses; 3) when evaluating in extreme conditions (straw moisture is close to 30% and straw content - 1:1.6), threshers with a larger value of the total effective length of the CTSS system have lower grain losses. Analysis of the Δq indicator model shows that grain losses are inversely proportional to the effective length of the CTSS system. Analysis of the Δq indicator model shows that grain losses are inversely proportional to the effective length of the CTSS system. The intensity of the processes of threshing, separation and cleaning of grain in the thresher is largely determined by the condition of the technological mass - the moisture content of the straw and its quantity (strawness). According to them, the processes of separating grain from straw have different degrees of intensity and, accordingly, the level of losses. Conclusions. Losses of grain behind the thresher of the grain harvester are simulated with a sufficient degree of reliability. The basis of mathematical modeling of the grain loss indicator is the application of a multifactorial experiment. The developed mathematical multifactor model of the grain loss indicator with a probability of 0.95 characterizes the dependence of losses on the effective length of the complex grain separation system, the supply of technological mass to the threshing floor, the strawness of the bread mass and the moisture content of the straw. Key words: grain harvester, drum-type thresher, complex threshing-separating system, grain losses behind the thresher, mathematical modeling.