Fast Gas-Solid Flow Simulation for Air Seeder ControlApplications

摘要

Air seeders distribute seed and fertilizers through pneumatic conveying. Current practice uses excessive conveying speeds to reduce the risk of blockages within the conveying lines at the expense of greater waste, energy consumption and hydraulic requirements. Incorporating active control mechanisms has been theorized as a potential means of improving performance of the highly coupled and distributed conveying system. Fast prediction of two-phase flow conditions within the conveying system is a prerequisite for the proposed control strategies. The objective of this research was to develop a model and simulation for predicting flow in the conveying system suitable for control application.A low-computational cost, one-dimensional model and simulation were developed for efficient prediction of bulk two-phase flow conditions within the conveying system. The model is a simplified form of the Eulerian-Eulerian (two-fluid) equations for fluid-particle flows and was solved using computational fluid dynamics techniques implemented in MATLAB. Experiments were conducted which approximated a straight horizontal pneumatic conveying line for the purpose of validating simulation results. Tests consisted of dilute flow using spherical plastic particles with a diameter of 3.56 mm and covered mass loadings of 0.84 to 3.13. Simulation performance with respect to computing time was also examined.Simulated results were found to have good accuracy over the conditions examined. Average error between simulated and experimental solids velocity ranged between 6.33 and 17.37 %, while the average error for fluid pressure ranged between 5.85 and 9.38 %.Furthermore, program execution time was found to be less than the simulated time in all cases. Assessment of the developed model and simulation concluded that a suitable potential for control application exists. The prescribed methodology provides a foundation for future work and demonstrates the potential to incorporate fast gas-solid flow simulation into control infrastructure to improve the performance of the air seeder conveying system.