基于CFD离散相模型雾滴沉积特性的模拟分析

Simulation analysis on characteristics of droplet deposition base on CFD discrete phase model

为分析三维空间中气流对雾滴飘移的影响,该文基于计算流体力学(computational fluid dynamics,CFD)离散相模型的粒子跟踪技术,研究了不同喷雾条件下的雾滴特性。该文在条件为3m×2m×2m的长方体计算区域,喷嘴置于长方体顶端(上表面的几何中心),在合适的边界条件参数下,对喷雾高度为0.25～2m,风速为0～3m/s变化范围内的雾滴沉积特性进行了分析。结果显示,雾滴的分布趋势(偏移量)随风速和喷雾高度大小而变化:雾滴的沉积量随喷雾高度和风速的增加逐渐减小,其最大值为100%(喷雾高度为0.25m,风速为0),最小值为7.2%(喷雾高度为2m,风速为3m/s),其沉积率最大值和最小值分别为79.07%和3.98%,并基于该方法建立了雾滴沉积量和沉积率的预测模型。该研究为精量施药提供参考。

In order to analyze the effect on the droplet drifting made by the airflow, the discrete phase particle tracking technology was used to get the characteristics of the droplet deposition in different spraying conditions, based on the CFD theory. The virtual cube was in the dimension of 3 m×2 m×2 m with a sprayer nozzle at the top （ the geometrical center of abaxial surface for cube）. The characteristics of droplet deposition were simulated with the optimized boundary conditions at the different height of deposition, ranging from 0.25 to 2 m, and at the different speed of the wind, from 0 to 3 m/s. The results showed that the distribution of the droplets were different at the different speed of the wind. The droplet deposition decreased when both the height of the droplet section and the speed of the wind increased, of which the maximum was 100 %（at the height of 0.25 m and the speed of 0）, and the minimum was 7.2%（at the height of 2 m and the speed of 3 m/s）. The maximum and minimum of droplet deposition ratio was 79.07%, 3.98%, respectively, and prediction models of the droplet deposition and the droplet ratio were established based on technology mentioned in this paper, which provides a reference for precise pesticide application.