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针对水稻直播高速作业和大播量的要求,设计了一种适用于气力集排式水稻直播机的分种器。从直播机的适应性、作业速度、播量调节等方面研究了气力集排式分种器的分种机理,分析了分种器的适应性、均匀性和稳定性;根据水稻种子的物理特性,采用Solidworks Flow软件进行计算流体动力学(computational fluid dynamics,CFD)仿真,对比不同结构分种器速度流场分布图,得到了较优等种数流场,获得了分种器设计参数;分种器划分为等种数流场结构、输送结构、下种结构,等种数流场结构又分为聚种、分种、派种3部分,通过理论分析与流体仿真计算,对比速度大小和离散度,模拟等种数速度场流线图,优化分种盖结构,选择合适的气源,设计了气种混合均匀的分种器,提高了直播机分种的均匀性和稳定性。试制了分种器并进行了台架试验,试验结果与CFD仿真分析基本一致,设计的10行分种器各行之间和行内播量变异系数分别为3.58%和4.55%,设计的20行分种器各行之间和行内播量变异系数分别为3.91%和5.04%,能满足不同直播机的要求。试验结果表明,直管输送管增加波纹结构有助于水稻种子向管道中央集聚;排种管的长短影响分种效果,特别是行内的稳定性,排种管的长度应尽可能一致;分种器内部结构影响气体速度场的分布,分种器内外盖形成的等距圆弧结构和输送管内波纹结构有利于分种器中气种等种数混合流场的形成,使播种均匀性更好。
In view of the requirements of high-speed direct-seeded rice and large seeding capacity, a seed-type selector suitable for the air-laid rice direct seeding machine was designed. The seed-collecting mechanism of the pneumatic manifold-type seed-seeding machine was studied from the aspects of the adaptability, working speed and sowing adjustment of the direct seeding machine. The adaptability, uniformity and stability of the seed-sorter were analyzed. According to the physical characteristics of the rice seed, , The computational fluid dynamics (CFD) simulation was carried out by using Solidworks Flow software. Compared with the flow field distribution of different structures, the optimal flow field of species was obtained and the design parameters of the seed was obtained. The device is divided into equal number of flow field structure, transport structure, under the kind of structure, and other species flow field structure is divided into three kinds of seed, seed, and seed distribution, through theoretical analysis and fluid simulation calculation, the contrast speed size and discrete Degree, and simulation speed maps of various species, optimize the seed cover structure, select the appropriate gas source, design a gas species mixed uniform seed, improve the uniformity and stability of the direct seeding points. The experimental results were basically consistent with the CFD simulation analysis. The coefficient of variation of the sowing rate of the 10 rows of splitters between the rows and the rows were 3.58% and 4.55% respectively. The designed 20 rows of points The variation coefficient of sowing amount between rows and rows of sowing plants were 3.91% and 5.04% respectively, which could meet the requirements of different direct seeding machines. The results showed that the corrugated structure of the straight pipe was helpful for the concentration of rice seeds to the center of the pipe. The length of the seeding pipe affected the seeding effect, especially the in-line stability and the length of the seeding pipe should be as same as possible. The internal structure of the device affects the distribution of the gas velocity field. The equidistant circular arc structure formed by the inner and outer caps of the splitter and the corrugated structure inside the delivery pipe are favorable for the formation of a mixed flow field of gas species and other species in the splitter, so that the sowing uniformity is better .