基于CFD-DEM耦合的膨化颗粒饲料气力输送机理数值分析

Numerical Analysis of Pneumatic Conveying Performance of Expanded Pellet Feed Based on CFD-DEM Coupling

摘要:

气力输送是水产饲喂的主要方式之一，然而目前气力输送过程中颗粒运动机理尚不清晰，以致气力输送系统的作业效率难以提升。本文以膨化颗粒饲料为对象，采用CFD-DEM气固耦合数值分析方法，构建双弯管颗粒饲料气力输送过程的数值分析模型，采用Box-Behnken响应曲面法量化分析喂料速率、入口风速、弯管数对颗粒饲料料气输送比、出口速度和悬浮程度的影响。方差分析结果显示：喂料速率显著影响料气输送比。各因素对颗粒饲料末端速度影响由强到弱为入口风速、弯管数、喂料速率，各因素对颗粒饲料悬浮程度影响由强到弱为入口风速、喂料速率、弯管数。入口风速与颗粒的出口速度和颗粒在竖直方向的坐标、标准差成正比，当喂料速率小于35g/s时入口风速对料气输送比无显著影响。随着入口风速提高，颗粒的出口速度提高，颗粒悬浮程度上升，表明气力输送系统的输送性能增强。当入口风速为20m/s、喂料速率为27.232g/s、无弯管时，料气输送比为0.966，颗粒出口速度为12.48m/s，竖直方向坐标为-3.944mm，标准差为8.805mm。研究结果为提升气力输送系统的效率和优化设计提供了理论依据。

Abstract:

Pneumatic conveying is one of the main methods in the field of aquatic feeding. However, the mechanism of particle movement in the pneumatic conveying process is not fully understood at present, making it challenging to improve the operational efficiency of the pneumatic conveying system. The CFD-DEM gas-solid coupling numerical analysis method was utilized to construct a model for the pneumatic conveying process of granular feed, specifically focusing on systems with double bends. Additionally, the Box-Behnken response surface method was employed to quantitatively analyze the effects of inlet wind speed, feeding rate, and the number of bends on various parameters, including the ratio of granular feed material conveyed, the exit speed of particles, and the degree of levitation. The results of the sensitivity analysis indicated that the factors influencing the model response indexes in descending order of importance were as follows: inlet wind speed, feeding rate, and the number of bends. Specifically, the inlet wind speed was directly proportional to the velocity of the particle outlet and influenced the vertical coordinates and standard deviation of the particles. Notably, the inlet wind speed did not significantly affect the material-air transport ratio when the feeding rate was below 35g/s. As the inlet wind speed increased, both the exit velocity of particles and the degree of particle suspension were risen, suggesting an enhancement in the conveying performance of the pneumatic conveying system. Under optimal conditions, specifically, an inlet wind speed of 20m/s, a feeding rate of 27.232g/s, and a system without elbows-the material-air conveying ratio reached 0.966, the exit velocity of particles was 12.48m/s, the vertical coordinate of particles was -3.944mm, and the standard deviation was 8.805mm. The findings can provide a theoretical foundation for improving the efficiency of pneumatic conveying systems and optimizing their design.