气吸滚筒式排种器吸种过程的动力学分析

Dynamic analysis on seeds pick-up process for vacuum-cylinder seeder

为了分析工作参数对气吸滚筒式排种器吸种性能的影响,建立了种子和滚筒的三维模型,在恒压力边界条件下,运用Fluent软件计算种子在真实吸种气流场中的受力,并采用中心差分法求解种子运动方程,得到种子吸附瞬态运动轨迹为:首先在轴向吸力的作用下,种子沿种盘作水平运动;随着滚筒的转动,种子受到的径向吸力迅速增大,并从种盘上被吸起,与滚筒发生碰撞后,沿壁面向着吸孔中心滑移,最终被吸孔吸附。排种器的吸种性能随滚筒转速的提高而降低,随负压差的升高而增强。以油菜种子为对象,在自制的排种器上进行性能试验,结果表明,当负压差为3～4kPa、滚筒转速在15r/min附近时,排种器的播种合格指数超过95%,为排种器的结构调整和工作参数优化提供了依据。

3-D models of rape seeds and vacuum cylinder were established to analyze the influence of working parameters on pick-up performance of vacuum-cylinder precision seeder.In constant pressure boundary condition,software Fluent was used to calculate the suction forces action on seeds in the gas field nearby vacuum nozzle.Seed motion differential equation was derived using central difference method and then the typical suction trajectory was received which could be described as：seed moved on the horizontal plate firstly under the suction of axial force,then,the radial suction force increased quickly with the rotation of vacuum cylinder,seed could be sucked up from the plate and slipped towards the vacuum nozzle.Suction ability of seeder can be enhanced with the increasing of differential vacuum pressure and be decreased with the increasing of cylinder rotational speed.Rape seeds were selected as experimental materials and experiments were carried out on precision seeder test-rig.Experimental results indicate that the maximal qualified index of more than 95% is received with the cylinder rotational speed and the differential vacuum pressure of 15 r/min and 3～4 kPa.The study provides a basis for the structural adjustment and working parameter optimization of the seeder.