基于CFD-DEM的排肥用波纹管结构优化设计与试验

为探究波纹管结构参数与输送均匀性的关系，获得最优参数组合以提高气力排肥均匀性。本文基于CFD-DEM耦合仿真技术构建了以排肥均匀性变异系数为响应值的二次响应面模型，在单因素试验的基础上采用BDD法研究了波纹管幅宽、波纹间距和波长之间交互作用对排肥均匀性的影响，并获得了波纹管的最佳参数组合，最后进行台架试验对仿真模型与优化结果进行验证。仿真试验结果表明，排肥均匀性变异系数随波长、幅宽、波纹间距的增加先减小后增加，波纹管结构参数对排肥均匀性的影响显著性顺序为幅宽>波长>波纹间距。波纹管最优结构参数为波长18.103 mm,波纹间距12.158 mm,幅宽8.863 mm,此时排肥均匀性变异系数为7.5%。单因素台架试验中尿素颗粒仿真预测值与台架实际值变化趋势一致，数值基本重合，最优参数组合波纹管排肥均匀性变异系数与仿真试验预测值相对误差的均值为5.84%,说明仿真模型精确可靠。复合肥颗粒变化趋势与尿素颗粒基本一致，说明仿真模型具有普适性。本研究可为波纹管的使用与优化提供参考。

Numerical analysis of flow characteristics and structural optimization of bellows based on CFD-DEM

In order to explore the relationship between bellows structural parameters and conveying uniformity, the optimal parameter combination was obtained to improve the uniformity of pneumatic fertilizer discharge. Based on CFD-DEM coupling simulation technology, this paper constructed a quadratic response surface model with the variation coefficient of fertilizer discharge uniformity as the response value. On the basis of single factor test, BDD method was used to study the influence of the interaction between bellows width, bellows spacing and wavelength on fertilizer discharge uniformity, and the best parameter combination of bellows was obtained, Finally, the bench test was carried out to verify the simulation model and optimization results. The simulation results showed that the variation coefficient of fertilizer discharge uniformity firstly decreased and then increased with the increase of wavelength, width and ripple spacing. The order of significance of the influence of bellows structural parameters on fertilizer discharge uniformity was width>wavelength>ripple spacing. The optimal structural parameters of bellows were wavelength 18.103 mm, ripple spacing 12.158 mm and width 8.863 mm. At this time, the variation coefficient of fertilizer discharge uniformity was 7.5%. In the single factor bench test, the change trend of urea particle simulation predicted value was consistent with the actual value of the bench, and the values basically coincided. The average value of the relative error between the variation coefficient of corrugated pipe fertilizer discharge uniformity of the optimal parameter combination and the predicted value of the simulation test was 5.84%, which showed that the simulation model was accurate and reliable. The change trend of compound fertilizer particles was basically consistent with that of urea particles, which showed that the simulation model was universal. This study can provide a reference for the use and optimization of bellows.