Experimental study of the effects of discharge port parameters on the fertilizing performance for fertilizer distribution apparatus with screw

As an ideal execution mechanism for precise fertilizer distribution, the fertilizer distribution apparatus with screw is of great significance for precise fertilizer distribution. To solve the problem that the fertilizer flow rate at the discharge port of the fertilizer distribution apparatus with screw fluctuates with time during the fertilizer transportation process and the low fertilization precision, the orthogonal experiments and bench experiments, taking the variable coefficient of fertilization uniformity as the evaluation indexes, were carried out to study the influences of the discharge port parameters of the screw fertilizer distribution apparatus on the fertilization performance with the discrete element simulation and 3D rapid prototyping technology. The screw fertilizer distribution apparatus consisted of feeding inlet, screw, screw shell, discharge port. Firstly, A discrete element simulation platform was established to analyze the transient characteristics of the screw fertilizer distribution apparatus, the results showed that the lateral fertilizer method can reduce the low-frequency pulsation in the screw fertilizer process. Moreover, single-element tests with discrete element simulation of the discharge port angle and discharge port length were performed. The effective range of the discharge port angle and length were 120°-150° and 40-80 mm respectively according to single-element tests. Furthermore, the L18 (37) standard orthogonal table was used for the discrete element simulation and the bench test. The influences of two factors on the fertilization accuracy were studied, including the length of discharge port and the angle of discharge port and the interaction between the previous two factors. The fertilization characteristics of a single spiral rotation period are analyzed by orthogonal experiments. The results showed that the order of the main factors affecting the variable coefficient of fertilizer uniformity were the length of discharge port and the angle of discharge port, interaction between the previous two factors. The length of discharge port and the angle of discharge port had significant influences on the coefficient variation of uniformity of the fertilizer distribution apparatus with screw while the interaction between these two factors was not significant. The optimal combination of parameters was as follows: the length of the discharge port was 60 mm, the angle of discharge was 135°. The simulation results based on the optimal combination showed that the coefficient variation of uniformity was 4.98 %. The bench test was conducted to verify the optimal parameter combination results obtained by the orthogonal test. The bench verification test results showed that the coefficient variation of uniformity was 5.41 %, basically agree with the simulation result. This study can provide a reference and theoretical basis for the design and optimization of the fertilizer distribution apparatus with screw.