油菜联合收获机割台气吹式籽粒低损回收喷嘴设计与试验

Design and Testing of Air-blown Low-loss Seed Recovery Nozzles for Oilseed Rape Combine Harvester Cutting Decks

摘要:

针对油菜联合收获过程中机械碰撞角果炸荚导致割台掉粒损失大等问题，设计了一种割台气吹式籽粒低损回收装置，并对气力喷嘴关键部件进行了设计。为保证气流分布合理和回收效果，采用鸭嘴式结构设计了喷嘴结构形状，并配套设计了入禾器，实现割台低损收获。基于Fluent对喷嘴内部流场进行仿真，以喷嘴开口角度、喷嘴开口宽度为试验因素，以气流出口速度、气流宽度与气流相交距离为评价指标进行两因素全因子仿真试验。试验结果表明，当喷嘴开口角度为35°、喷嘴开口宽度为3 mm时，出口速度为138 m/s，气流宽度为1 926 mm，气流相交距离为64 mm，风幕覆盖效果最好；以喷嘴角度、横向距离、籽粒掉落高度为试验因素，回收量为评价指标开展了台架试验，喷嘴在割台上最佳布置参数组合为喷嘴角度19.6°、横向距离387 mm；田间试验结果表明，油菜割台损失率为2.48%，相比传统收获作业下降35.5%~50.4%，有效降低了割台损失，满足油菜低损收获作业要求。

Abstract:

Aiming at the problems such as big loss of grain dropped from the cutting table due to the mechanical collision of angular fruit frying pods in the process of oilseed rape combine harvesting, a low-loss recovery device of air blowing grain from the cutting table was designed, and the key components of the pneumatic nozzle were also designed. In order to ensure reasonable airflow distribution and recovery effect, the nozzle structure shape was designed by adopting the duckbill structure, and the supporting design of the harvesting device was made to realize the smooth operation of low-loss harvesting on the cutting table. Based on Fluent, the internal flow field of the nozzle was simulated, and the two-factor full factorial simulation test was carried out with the nozzle opening angle and nozzle opening width as the test factors, and with the airflow exit velocity, airflow width and airflow intersection distance as the evaluation indexes. The test results showed that when the nozzle opening angle was 35°, the nozzle opening size was 3 mm, the exit velocity was 138 m/s, the airflow width was 1 926 mm, and the airflow intersection distance was 64 mm, the wind screen coverage effect was the best;the bench test was carried out with the nozzle angle, transverse distance, and kernel drop height as the test factors, and the recycling volume as the evaluation index, and the optimal combinations of the nozzle arrangement parameters in the cutting table were as follows: nozzle angle was 19.6°, lateral distance was 387 mm;field test results showed that the oilseed rape cutting table loss rate was 2.48%, compared with the traditional harvesting operations, it was down by 35.5%~50.4%, effectively reducing the cutting table loss, to meet the oilseed rape low-loss harvesting operation requirements.