基于EDEM-Fluent耦合的颗粒肥料悬浮速度测定试验

为提供气力施肥装置的设计参考依据,以大颗粒尿素、磷酸二铵和硫酸钾3种颗粒状化肥为试验对象,通过计算流体动力学和离散元法耦合的方法对物料悬浮速度进行数值模拟,采用Lagrangian模型进行气固两相流耦合仿真,试验结果表明,大颗粒尿素悬浮速度7. 21～12. 97 m/s,磷酸二铵悬浮速度7. 68～12. 48 m/s,硫酸钾悬浮速度11. 09～18. 15 m/s。通过台架试验测定大颗粒尿素悬浮速度6. 68～12. 48 m/s、磷酸二铵悬浮速度7. 22～11. 96 m/s、硫酸钾悬浮速度9. 46～17. 81 m/s,相对误差分别为5. 3%、5. 1%、7. 2%。在颗粒肥料体积分数1. 0%、3. 5%、6. 0%、8. 5%时,分别测定肥料颗粒群的悬浮速度,结果表明,颗粒群悬浮速度随着体积分数的增加而减小,在不同颗粒肥料体积分数下,仿真结果与试验结果相对误差近似为常数,其原因为颗粒球形度对悬浮速度的影响,标定得出大颗粒尿素悬浮速度修正系数0. 90、磷酸二铵悬浮速度修正系数0. 96、硫酸钾悬浮速度修正系数0. 84。基于流固耦合的颗粒悬浮速度仿真具有较高的准确度,验证了基于EDEM-Fluent气固两相流耦合仿真测定物料悬浮速度方法的可行性。

Test of Suspension Velocity of Granular Fertilizer Based on EDEM-Fluent Coupling

Suspension velocity is one of the main aerodynamic characteristics of materials, and it is an important basic data for the design of pneumatic conveying system. A reference for the design of pneumatic fertilization device was provided, and three kinds of granular fertilizers of large granular urea, diammonium phosphate and potassium sulfate were taken as test objects. The suspension velocity of materials was simulated by the coupling method of computational fluid dynamics and discrete element method. The Lagrangian model was used to simulate the gas-solid two-phase flow. The experimental results showed that the suspension velocity of large granular urea was 7.21~12.97m/s, the suspension velocity of diammonium phosphate was 7.68~12.48m/s, and the suspension velocity of potassium sulfate was 11.09~18.15m/s. Through the bench test, the suspension velocity of large granular urea was 6.68~12.48m/s, diammonium phosphate was 7.22~11.96m/s, potassium sulfate was 9.46~17.81m/s, the relative errors were 5.3%, 5.1% and 7.2%, respectively. When the volume fraction of granular fertilizer was 1.0%, 3.5%, 6.0% and 8.5%, the suspension speed of granular fertilizer group was measured. The suspension speed of granular fertilizer group was decreased with the increase of volume fraction. Under different volume fractions of granular fertilizer, the ratio of simulation test results to real test results was approximately constant, which was supposed to be due to the influence of particle sphericity on suspension speed. The results showed that the correction coefficient of the suspension velocity of large granular urea was 0.90, that of diammonium phosphate was 0.96, and that of potassium sulfate was 0.84. Therefore, the simulation test of particle suspension velocity through fluid solid coupling simulation had a high accuracy, which verified the feasibility of the method of measuring the suspension velocity of materials based on EDEM-Fluent gas-solid two-phase flow coupling simulation, and provided a new method for measuring the suspension velocity of agricultural materials.