油麦兼用气送式排种系统高通量混种装置设计与试验

Design and Text of High-throughput Seed Mixing Device for Rapeseed and Wheat with Air-fed Seed Discharging System

摘要:

针对气送式排种系统在排种量增大时混种装置内易出现种子回流、堵塞等现象，导致排种系统高速播种作业适应性较差的问题，设计了一种突扩文丘里结构的高通量混种装置，通过理论分析确定了输种管直径、混种区长度、进种入口截面长度等关键结构参数；Fluent气流场仿真结果表明，当风速为12、15、18m/s时，文丘里结构的混种装置喉管处负压最小值分别为-236、-372、-538Pa，突扩文丘里结构的混种装置预混区负压最小值分别为-396、-621、-1007Pa，突扩文丘里结构产生的“文丘里效应”优于普通文丘里结构；DEM-CFD耦合仿真结果表明，在混种过程中突扩文丘里结构的混种装置存在约12%油菜种子与突扩文丘里结构延伸部分碰撞后弹跳，碰撞后种子保持向混种区方向运移，油菜和小麦均未出现回流、堵塞等现象。台架试验结果表明，传统文丘里结构的混种装置在油菜混种通量大于等于2.4g/s出现种子回流，小麦混种通量大于等于60g/s时出现种子回流且各行排量一致性变异系数显著增大、混种通量大于等于100g/s时发生堵塞；突扩文丘里结构的混种装置在油菜混种通量小于等于4.8g/s、小麦混种通量小于等于120g/s时未出现种子回流、堵塞等现象，油菜、小麦各行排量一致性变异系数低于5.17%、3.29%，总排量稳定性变异系数低于1.19%、0.80%，可满足油菜、小麦播种机速度为4~12km/h的农艺播量要求，研究结果为气送式排种系统结构优化提供参考。

Abstract:

Aiming at the air-fed seed discharging system in the seed discharging volume increases in the seed mixing device is prone to seed reflux, clogging and other phenomena, resulting in the discharge system of high-speed sowing operation of poor adaptability of the problem, the design of a sudden expansion of the Venturi structure of the high-throughput seed mixing device was done, through the theoretical analysis to determine the diameter of the seed tube, the length of the mixing zone, the length of the cross-section of the seed inlet length of the structure of the key parameters. Fluent airflow field simulation results showed that when the wind speed was 12m/s, 15m/s and 18m/s, the minimum negative pressure at the throat of the seed mixing device with Venturi structure was -236Pa, -372Pa and -538Pa, respectively, and the minimum negative pressure at the pre-mixing area of the seed mixing device with abruptly expanding Venturi structure was -396Pa, -621Pa and -1007Pa, respectively, and the “Venturi effect” produced by abruptly expanding Venturi structure was better than that of ordinary Venturi structure. The results of DEM-CFD coupled simulation showed that about 12% of rape seeds bounced after collision with the extended part of the Venturi structure, and after collision, the seeds kept moving towards the mixing area, and there was no phenomena of reflux and blockage in both rape and wheat. The results of bench test showed that the seed mixing device of traditional Venturi structure showed seed reflux at the seed mixing flux of oilseed rape greater than or equal to 2.4g/s, seed reflux at the seed mixing flux of wheat greater than or equal to 60g/s and the coefficient of variation of the consistency of the rows’ displacements were increased significantly, and clogging occurred at the seed mixing flux was greater than or equal to 100g/s;the seed mixing device of the amplified Venturi structure had seed reflux at the mixing flux of oilseed rape smaller than or equal to 4.8g/s, wheat seed mixing flux less than or equal to 120g/s did not appear seed reflux, clogging and other phenomena, oilseed rape, wheat rows discharge consistency coefficient of variation was lower than 5.17%, 3.29%, the total discharge stability coefficient of variation was lower than 1.19%, 0.80%, to meet the oilseed rape, wheat seeding machine can be in the speed of 4~12km/h agronomic sowing requirements, the results of the study for the air-fed seeding system structure optimization can provide a reference. The results can provide reference for the optimization of the structure of the air-fed seed discharge system.