Abstract: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.
