The gap between concave grid and drum, the threshing gap, is one of the important operating parameters that affects the performance of threshing devices. The different methods currently adopted on combine harvesters to adjust both the drum and the concave, results in concentric and non-concentric threshing gaps that have different influence on e threshing performance. The threshing process is complex, therefore, in order to analyse the influence of the threshing gap on performance, flexible rice straw models were built using the discrete element method to simulate the threshing processes of the two adjustment methods. Their respective movements, separation status and the distribution of the mixture of the threshed output were examined. Simulation results indicated that over the same time, drum adjustment produced better material separation and transportation capabilities and more evenly distributed output mixture in the reception box, compared with the concave adjustment. A threshing experiment on a combine harvester was performed in order to verify the simulation result and the output mixture distribution status was found to be consistent with the results of the simulations. The experimental results showed that threshing was more effectively improved by changing the threshing drum diameter although the threshing gap was more complicated to adjust.

中文翻译：

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同心与非同心脱粒间隙水稻脱粒性能模拟

凹格与滚筒之间的间隙，即脱粒间隙，是影响脱粒装置性能的重要运行参数之一。目前联合收割机采用不同的滚筒和凹面调整方法，导致同心和非同心脱粒间隙对脱粒性能的影响不同。脱粒过程较为复杂，为分析脱粒间隙对性能的影响，采用离散元法建立柔性稻草模型，模拟两种调整方式的脱粒过程。考察了它们各自的运动、分离状态和脱粒后混合物的分布情况。模拟结果表明，在同一时间，与凹面调整相比，滚筒调整产生更好的物料分离和运输能力，并且在接收箱中输出混合物分布更均匀。为了验证模拟结果，在联合收割机上进行了脱粒实验，发现输出混合物分布状态与模拟结果一致。试验结果表明，虽然脱粒间隙的调整较复杂，但通过改变脱粒滚筒直径能更有效地提高脱粒效果。为了验证模拟结果，在联合收割机上进行了脱粒实验，发现输出混合物分布状态与模拟结果一致。试验结果表明，虽然脱粒间隙的调整较复杂，但通过改变脱粒滚筒直径能更有效地提高脱粒效果。为了验证模拟结果，在联合收割机上进行了脱粒实验，发现输出混合物分布状态与模拟结果一致。试验结果表明，虽然脱粒间隙的调整较复杂，但通过改变脱粒滚筒直径能更有效地提高脱粒效果。