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- 2015
油菜籽粒在割台纵向正压气流场中漂移运动的数值模拟
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Abstract:
为降低油菜联合收获过程中的割台损失，提出使用正压气流收集下落籽粒的方法，探讨处于下落过程中的油菜籽粒在正压气流场中的漂移特性，并采用Fluent和EDEM软件气固耦合模拟籽粒在无秸秆正压气流场中的漂移运动过程，利用自制室内台架试验装置进行台架试验验证模拟结果。结果表明：在流场中无油菜植株及籽粒初始下落高度一定的情况下，收集单体对从喷嘴正上方下落籽粒的收集率，随单体竖直高度的增加呈先增大后减小趋势，且随收集单体纵向长度的增加而减小；当其他条件不变时，在一定范围内，气流速度值越大，收集装置的收集效果越好； 超出一定范围后，收集装置的收集效果又随气流速度值继续增大而减小。在收集单体竖直高度为435 mm、纵向长度为620 mm和籽粒初始下落高度为700 mm等条件下，模拟得出的最佳入口气流速度约为20 m/s，而台架试验得出的最佳出口气流速度约为30 m/s，此时模拟和实测得到的收集率分别达到97.30%和92.10%。
In order to decrease the cutting table loss rate of the rape combine harvester, a novel method to collect the falling rape seeds by airflow of positive pressure was proposed in this paper. To investigate the drifting characteristics of rape seed in the positive pressure airflow field, the movement process of the seeds was simulated by coupling of Fluent and EDEM. And then the results of the simulation were verified by a test bench. Experiments show that in an airflow field without stalks and with a certain initial height of the seeds, the collection amount of seeds falling from the position above nozzle increased first and then decreased with the ascending of the monomer vertical height, but descended with the increasing of the monomer longitudinal length. With the consistent structural parameters and exit conditions, in a certain range, the larger the airflow velocity value is, the better the collection effect is; outside of this range, the collection effect declined when the airflow velocity value continued to climb up. Under the condition that the collection monomer vertical height is 435 mm, the longitudinal length is 620 mm and the initial height of falling seeds is 700 mm, the optimum inlet airflow velocity of the simulation results is about 20 m/s, while the most preferably outlet airflow velocity of the bench test results is about 30 m/s. At this time, the corresponding collection rate of the seeds falling from the position above the nozzle is 97.30% and 92.10% respectively.
