2013 Annual Report
The discrete element method (DEM) will be used to model adventitious grain commingling in bucket elevator legs. Existing particle models for corn, soybeans, and wheat will be used to create grain handling models in 3-d and quasi-2-d. The models will be applied to full-scale legs to evaluate the effect of: (1) operating parameters (flow rate, grain type, and cleanout procedures) and (2) design factors (uptake side, boot size, and cup design) on adventitious commingling levels. Preferred operating conditions and design characteristics for reducing undesirable commingling will then be evaluated.
Simulations were performed to determine the parameters required for improved particle models for sound corn and wheat kernels for use in discrete element modeling of grain handling. The new models were compared to see which characterized bulk grain behavior best in simulations of: (1) bulk density measurements, (2) angle of repose tests, and (3) hopper flow. The parameters evaluated were particle restitution coefficient, static friction coefficients, rolling friction coefficients, particle size distribution, and shear modulus. Literature values for the bulk grain behavior were used when possible and supplemented with results from laboratory experiments of hopper flow characteristics at moisture content levels of 10%, 12%, and 14% wet basis. Data were also obtained for particle density and single kernel mass of corn and wheat infested with rice weevil and lesser grain borer, respectively; these data are being used to develop improved particle models for infested kernels mixed with sound kernels for developing best management practices for reducing unwanted commingling of infested grain in bucket elevator boots.